Question

A mother is 20 years older than her son. In 7 years the mother will be 3 times as old as her son. How old is each now?

Answer 1

son is 3 and mother is 23

Explanation:

let n be the son's age then mother is n + 20

in 7 years

son is n + 7 and mother is n + 20 + 7 = n + 27

the mother is then 3 times as old as her son , that is

n + 27 = 3(n + 7)

n + 27 = 3n + 21 ( subtract n from both sides )

27 = 2n + 21 ( subtract 21 from both sides )

6 = 2n ( divide both sides by 2 )

3 = n

that is the son is 3 years old and the mother is 3 + 20 = 23 years old