Question

A man who is 40 years old has three sons, ages 6, 3 and 1. In how many years will the combined age of his three sons equal 80% of his age? * 5 10 15 20

Answer 1

Answer:

8/10 (40 + x) = (6 + x) + (3 + x) + (1 + x)

(320 + 8x) / 10 = 3x + 10

8x + 320 = (3x + 10) 10

8x + 320 = 30x + 100

8x + 220 = 30x

220 = 22x

x = 10