Itd be c.180 because itd be 12 cars each hour so times 12 by 15
If she was to volunteer 32 hours and it is worth 20%, then that means 32 hours is 1/5 of her yearly hours. If you were to multiply her volunteer hours by five, then you are getting the year number of hours she has volunteered.
32 x 5 = 160
So, she volunteers 160 hours this year.