Word Problem

A student at St. F. X. decided to become his own employer by using his car as a taxi for the summer. It costs the student $693.00 to insure his car for the 4 months of summer. He spends $452.00 per month on gas. If he lives at home and has no other expenses for the 4 months of summer and charges an average of $7.00 per fare, how many fares will he have to get to be able to pay his tuition of $3280.00?

Solution: # of fares = (3280 + 4*452 + 693) / 7

Commentary: This is a problem that actually has a certain practical application.  Not because anybody is going to run his own taxi business during the summer (nobody does that.)  Not because it's about a university student.  But because it forces the student to think about expenses.  It's actually good practice in accounting because it makes the student think about whether expenses should be added or subtracted from his tuition total, and why.  This is the crux of the problem and I imagine that most wrong answers will be because the student subtracts, rather than adds, the expenses.  I actually quite like this word problem for this very reason.  Most word problems I think are just arithmetic in code.  But this one actually contains an important lesson about income and expenses.