The context of the following conversation is Austin had been working as a tutor to make extra money for the last two years.  He likes doing this to help pay for his college education.:
Austin says I've found a great way to earn extra money for college is to tutor a few evenings a week and on Saturdays..
The friend responds What do you tutor?.
Austin responds Mostly high school math, algebra and geometry specifically..
The friend responds Does it pay well?.
Austin responds Definitely.  I charge $25 an hour and I can easily make $300 or $400 a week..
The friend responds I should give that a try.  But not math!  History or English would be better subjects for me to tutor..