Question

On Monday, Sean bought 3 cookies and 5 cakes and spent $78.75. On Tuesday, Sean bought 8 cookies and 2 cakes and spent $40.

Find the price for one cookie and one cake.

Answer 1

1 cookie = $1.25 1 cake = $15

Explanation:

set up a system of equations:

let x = 1 cookie

let y = 1 cake

3x + 5y = 78.75

8x + 2y = 40

I multiplied the first equation by 2 to get: 6x + 10y = 157.50

I multiplied the second equation by -5 to get: -40x - 10y = -200.00

If you add both equations, the y-terms will be eliminated

-34x = -42.50

x = 1.25

Plug in 1.25 into equation to find value of y: 8(1.25) + 2y = 40

10 + 2y = 40

2y = 30

y = 15