Question

A mother is 20 years older than her son.ten years ago she was 3 times as old as her son then. Find their present ages

Answer 1

let present ages of child and mother be x and x+20 respectively....
10 yrs before their ages ....child- x-10,mother- 3(x-10)....
now to make the age of mother that was 10 yrs before equal to present age i.e.3(x-10)+10 ...we can add 10 in it......the equation formed will be...
x+20=3(x-10)+10
x+20=3x-30+10
x+20=3x-20
3x-x=20+20
2x=40
x=40/2
x=20
child's present age is 20 so mother's present age will be x+20=20+20=40yrs

Answer 2

Let the son's age be = x

The mother's age be = x+20

x+20-10 = 3(x-10)

x+10 = 3x-30

x-3x = -30-10

-2x = -40

both minus will be cut

2x = 40

x = 40/2

x = 20 (son's age)

mother's age = x+20

20+20=40