Salma received a $70 gift card for a coffee store. She used it in buying some coffee that cost $7.61 per pound. After buying the coffee, she had $39.56 left on her card. How many pounds of coffee did she buy?

4

Step-by-step explanation:

Amount spent on coffee = 70 - 39.56 = 30.44

One pound costs 7.61, how many will cost 30.44

7.61 : 1 = 30.44 : X

7.61 = 30.44/X

X = 30.44/7.61

X = 4

4 pounds

Step-by-step explanation:

Do 70 - 39.56 = 30.44 To see how much she spent

Do 30.44 / 7.61 = 4 To see how many pounds of coffee she had bought

it's equivalent, so we can say that its equal.

let's call the denominator x and the numerador is 18 less then denominator, x - 18.

multiply

2.x = 5.(x - 18)

2x = 5x - 90

90 = 5x - 2x

90 = 3x

x = 90/3

x = 30

so: