like the answer below, you can't spend more thatn 100% which is what you have
the question is worded badly
read it
if maxine spent 15 hours last week ant 18 hours this week, she spent 120% of this week doing homework
I would guess we shoudl compare the increase
if the question is like, this week is 120% of last week, the answer would be correct
because
18=120% of 15
18=1.2*15
18=18
true
but, if you only red the question, then
each week=7 days, 24 hours, 7*24=168
15/168=9%
18/168=11%
not even close to 120%
I would say that the time she spent this week was 120% of the time last week