Algebra word problem

Question

To make limeade punch you need 7 parts fruit punch to 3 parts limeade. If you want to fill a 1040 ounce bowl how many ounces of each do you need?

Answer 1

7 parts fruit punch to 3 parts limeade, 7+3=10

14 parts fruit punch to 6 parts limeade, 14+6=20

21 parts fruit punch to 9 parts limeade, 21+9=30

and so on until we get a sum equal to 1040

we want to multiply 7 and 3 by the same number and add the two products to get 1040

let x be that number

7x+3x=1040

10x=1040

x=1040/10

x=104

multiply 7 by 104 and multiply 3 by 104

7*104=728 ounces of fruit punch

3*104=312 ounces of limeade

728+312=1040