In any case, if they're the same sign, then $g-a$ would predict that, when travelling upwards at $9.8\ \rm m/s^2$, I feel $9.8-9.8=0$ gravitational force
@ErikM If they're both less than $i$, nothing happens. If they're both greater than $i$, they both get $1$ subtracted. If one is smaller than $i$ and one is greater than $i$, then you subtract one from the greater one, and you end up with a $<i$ and $\ge i$
The simplest way to get to the right conclusion is to think in terms of the equivalence principle. The reason why the pendulum moved backward is that, when the train speeds up, its acceleration translates into an additional backwards force in the train's reference frame.
But there's already the weight of the pendulum, which points straight down.
But some of my colleagues did require LaTeXing of (some) homeworks. When my students turned in LaTeXed homework, I actually then had to correct their LaTeX (to teach them how to do stuff). Of course I didn't grade on that.
I'd also say it's pretty much required for any course which involves some kind of math research project. But term papers aren't so much a thing in math.
