joyce wants to mix granola and raisins together to make a snack for her class. granola costs $2 per pound and raisins cost $4.50 per pound. joyce is willing to spend $37.50 and wants to make 15 pounds of trail mix. which system of equations could joyce use to figure out how many pounds of granola (g) and raisins (r) she should buy?
a)
b)
c)
d)