Answer:
Kristen bought 2 fancy shirts and 5 plain t-shirts.
Step-by-step explanation:
Given that,
Kristen spent $131 on 7 shirts.
Cost of one fancy shirt = $28
Cost of one plain t-shirt = $15
Let,
x be the number of fancy shirts
y be the number of plain t-shirts
x+y = 7 Eqn 1
28x+15y=131 Eqn 2
Multiplying Eqn 1 by 15
15(x+y=7)
15x+15y=105 Eqn 3
Subtracting Eqn 3 from Eqn 2
(28x+15y)-(15x+15y)=131-105
28x+15y-15x+15y=26
13x=26
Dividing both sides by 13
Putting x=2 in Eqn 1
2+y=7
y=7-2
y=5
Hence,
Kristen bought 2 fancy shirts and 5 plain t-shirts.