math
posted by rock on .
on his first exam, he studied for 10 hours and went to tell the mall for 4hours, and got a score of 85. how long should he study to get a grade of 96 and go to the mall for 17 hours?
grade varies directly with studying and inversely with going to the mall.
is the answer 48hrs?

Mark = k(s)/m, where s is number of hrs studying, m is the number of hrs at the mall, and k is a constant
given: Mark = 85, s=10, m=4
85 = k(10)/4
k = 34
Mark = 34s/m
96 = 34s/17
s = 48 hrs
(a rather silly question)