The morning I started to suspect that Ms. Pendleton’s equation had some holes in it, I was late for school. Mom and I were on the way to the Metro; we share a car, and on the days I have stuff to do after school I drop her off to take the train into Arlington. We’re a well-oiled machine in the morning; to get both of us where we need to be on time, we have to go out the front door by 7:10. This gives us fifteen extra minutes of wiggle room in case we hit traffic, or someone spills coffee on themselves and has to change again, or whatever.

Mom was driving so I’d have time to eat a bagel before I had to switch seats at the station, and with my free hand I was fiddling with the radio, bouncing back and forth between the morning news, which my mom wanted to listen to, and the music I was listening to during the commercials. I wasn’t really 100% awake yet; I hoped she was, because she was driving, and then there was a huge clunk followed by rattle-rattle-rattle, and then my mother looked in the rearview mirror and said, “Holy crap.” I turned and looked, and there were sparks coming from the back of the car.

“Pull over,” I said, dropping my bagel. “Pull over, pull over, WE ARE ON FIRE.”

“I’m working on it,” she said through gritted teeth. “It’s not on fire. Yet.”

“There are sparks!”

“I’m aware of the sparks! Can I get to the right?”

My mom is always doing this thing where I have to copilot and tell her if she can merge. I have no idea what she does when I’m not in the car. “It’s fine,” I said. “Just go. Go. Go like you mean it. No, wait. Wait!” This last bit was because she’d waited too long, and there was a truck bearing down on us from the right lane.

“You said I could go!” she shouted, jerking back into her lane.

“You could have, when I actually said it!”

“I was merging!”

“You flinched! You can’t flinch on 95!”

“I think there might be fire now,” she said. “Do you smell that?”

“Get over,” I said. “Get over get over get over.”

She merged and pulled over to the shoulder. The car made an ungodly scraping sound as it came to a stop.

Both of us turned to look out the back window. I couldn’t see any flames, but there was smoke, and something smelled like burnt motor oil.

“What happened?” I said, still looking out the rear window, hoping that nothing was getting ready to explode back there.

“Muffler, I think,” she said. She got out of the car and went around to the back, and I followed. “Oof,” she said. The muffler had indeed detached itself from the bottom of the car and was being dragged on the asphalt by whatever it was attached to on the other end. A bolt? I have no idea what holds mufflers on.

“I’m thinking that’s bad?” I said.

“It’s bad.”

“Can you, like, put it back? Maybe with duct tape?”

“Duct tape,” she said, mulling it over. “No, we’ll have to get it towed.”

“Great,” I said. “I’m supposed to be in calculus in half an hour.” I pulled out my phone and started texting to see if anyone could come and pick me up, but it was still early, and nobody answered.

“Nate?” Mom said. “Caroline?”

“Still asleep,” I said. “They’re not answering.”

“Well, you’ll just have to go in a cab,” she said.

“Mom,” I said. “I don’t think--”

“It’s fine.”

“A Lyft would be cheaper,” I said.

“I’m not putting my eighteen-year-old in a Lyft,” she said. “Anybody could be driving it.”

“Do you know how much a cab is going to cost?”

Stupid question. She knew exactly how much it would cost.

“Here’s what’s happening,” she said. “You’re going to school in a cab. I’m going to wait here for the tow truck.” She rubbed her face with her hand. “I had a nine o’clock meeting today.”

We stared at the dead car. I don’t usually think about how much depends on a big chunk of metal and an internal combustion engine, but one sheared-off bolt was all it took to set us scrambling. The car repair and the cab would both end up on the credit card, my mom would miss her meeting, and if I was very lucky, I wouldn’t miss a pop quiz in calculus.

Ten minutes later my cab showed up. I gave the driver directions to my school and then sat back to listen to twenty minutes of the second act of Hamilton, plus three different cell phone conversations in Amharic. Then Hamilton died (both literally and metaphorically) and the music ended, and then the driver was singing along with Evita, and I guess the driver had watched too much Phantom of the Opera because he kept saying “Sing! SING!” and seemed annoyed that all I knew was the chorus, and also that I really don’t sing all that well.

I got out after the second verse of “Don’t Cry for Me, Argentina,” shutting the door as the driver belted out They are illooooooosions . . . and wondering if this guy had had theatrical aspirations before settling down as a cab driver, because he sang like a dream but did not seem to know how to, like, parallel park.

The forty-dollar cab got me to school ten minutes past the bell, and I had to sprint through the building, racing past Mr. Pelletier, the assistant head, who looked like he would really have liked to give me service hours, except he was already in the middle of giving service hours to someone else.

The rest of my calculus class was still half-asleep as I slid into my chair, sweaty and panting, but Mr. Bronstein frowned at me as I pulled out my notebook. “Miss Abramavicius,” he said. “You are aware that your grades this quarter will be sent to your college?”

“Yes, sir,” I said, still puffing.

“And we still have the AP exam coming up,” he went on. “Unless you are looking forward to repeating this class in college with a less understanding instructor.” He pointed at me with his dry-erase pen. “One who locks the latecomers out of the classroom.”

I wondered if that was an actual thing that happened. “I’m sorry,” I said. “My mom’s car died.”

He nodded thoughtfully. I was a “special case” at Blanchard because I was a senior and I didn’t have my own car. I wasn’t the only person there on a scholarship, not by a long shot, but I spent less time trying to pretend than the others. We aren’t poor, but the tuition at Blanchard is almost as much as my mother makes in a year, and I don’t think it’s particularly shameful not to have a cool forty thousand dollars a year sitting around collecting dust. The school fronted me three-quarters of my tuition, and my mother went broke paying the last bit.

“This is the best education you can get,” Mom said when we went without things like vacations or new shoes or takeout. “You know, we live in a global economy. You’re competing against people from all over the world. That’s how things are now.”

It was a speech I heard often. It wasn’t enough to compete against the kids from my school, or the mid-Atlantic, or the US. I was competing against people from China and Germany and Brazil, and would be for the rest of my life. How many people are there these days? Seven billion? The idea of all those people fighting for all the same things I wanted weighed on me. It was like circling the parking lot at the mall on Christmas Eve and discovering that there was one spot left--and several million people were already there, lined up to snatch it. If I thought about it too much, it made my head hurt.

Mr. Bronstein turned back toward the board and started discussing derivatives, which I already knew how to do, and I absentmindedly took some notes on what he was saying. My phone buzzed in my purse, and after deciding that no one was paying attention, I fished it out of my bag and stashed it on my knee.

It was a text from Caroline Black, who was sitting two rows behind me on the other side of the room.

Did you hear? she texted

Hear what?

Oh my God, it’s Admissions Day. You did NOT forget.