Kristin spent $131 on shirts. fancy shirts cost $28 and plain shirts cost $15. if she brought a total of 7 then how many of each kind did she buy?
f = fancy total cost 28 f
(7-f) = p = plain total cost of plains 15 (7-f) summed, the costs are 131
28f + 15 (7-f) = 131 solve for f, the number of fancy shirts..... then plains = 7-f