Question

How do you solve this problem using system of equations

Kristin 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?

Answer 1

Create our system of equations
28f + 15p = 131
f + p = 7

Solve for f or p (it doesn't matter which)
f = 7 - p

Put this into the other equation above
28f + 15p = 131
28(7 - p) + 15p = 131

Solve
196 - 28p + 15p = 131
196 -13p = 131
-13p = -65
p = 5

Answer:
p = 5
f = 2