Lena received a $90 gift card for a coffee store. She used it in buying some coffee that cost $8.32 per pound. After buying the coffee, she had $65.04 left on her card. How many pounds of coffee did she buy?

Explanation:

x = number of pounds of coffee

1 pound costs 8.32 dollars

Multiply both quantities by x to show that x pounds cost 8.32x dollars.

Subtract this amount from the $90 and 90-8.32x represents how much is left on the card, which we're told is $65.04

Therefore, the equation to solve is 90-8.32x = 65.04

Solving said equation leads us to...

90-8.32x = 65.04

-8.32x = 65.04-90

-8.32x = -24.96

x = -24.96/(-8.32)

x = 3

Lena bought 3 pounds of coffee

Check:

1 pound = $8.32

3 pounds = 8.32*3 = 24.96 dollars

90 - 24.96 = 65.04 which matches what we're told she had left on the card. The answer is confirmed.

the answer to the expression is 83