Kristen spent $131 on shirts. Fancy shirts cost $28 and plain shirts cost $15. If she bought a total of 7 then how many of each kind did she buy?
Equations are x+y=7 and 28x+15y=131
x+y=7 → y =7 − x
28x+15( 7 − x ) =131
28x + 105 − 15x = 131
13x + 105 = 131 subtract 105 from both sides
13x = 26 divide both sides by 13
x = 2 = fancy shrts bought
y =7 − 2 = 5 plain shirts bought
