A high school student council wants to purchase spirits shirts for its upcoming honecoming event. purchases of 25 shirts or less costs 20 per shirt, plus 20 shipping and handling. when more than 25 shirts are odered, the price is 15 per shirt, plus 15 shipping and handling. if 720 was spent on shorts, how many shirts did the student council order

a) 30 shirts
b) 40 shirts
c) 45 shirts
d) 50 shirts