Question

Three boxes have a total weight of 640 pounds. Box A weights twice as much as Box B. Box C weight 30 pounds more than Box A. How much do each of the boxes weigh?

Answer 1

A: 244 pounds

B: 122 pounds

C: 274 pounds

Explanation:

We have A+B+C = 640; A=2B; C=A+30. Substituting the last into the first gives ...

A + B + (A +30) = 640

2A +B = 610 . . . . . . . . . . . . subtract 30

Substituting the second into this equation gives ...

2(2B) +B = 610

B = 610/5 = 122 . . . . . divide by 5

A = 2B = 244 . . . . . . . .find A from B

C = A+30 = 274 . . . . . find C from A

Box A weighs 244 pounds; box B weighs 122 pounds; box C weighs 274 pounds.