Question

The school is selling cookies and shirts. Cookies sell for $10 and shirts sell for $20 each. A total of 390 items were sold and $6500 was raised. How many of each items were sold?

Answer 1

130 cookies were sold

260 shirts were sold

Explanation:

c = cookies

s = shirts

the 2 equations are:

c + s = 390

10c + 20s = 6500

switch any of the variables in the first equation to the otger side, with the 390 ( i switched s)

c = 390 - s

now substitute 390 - s for c in the 2nd equation

10(390 - s) + 20s = 6500

now distibute

3900 - 10s + 20s = 6500

subtract the variables

3900 + 10s = 6500

subtract 3900 from 6500

10s = 6500 - 3900

10s = 2600

divide 2600 by 10

s = 2600÷10

s = 260

so 260 shirts were sold

now substitute s for 260 in the first equation

c = s - 390

c = 260 - 390

c = 130

so 130 cookies were sold