Question

The father told his daughter, "I was four years old when I was your age." I will be 4 years old when you are my age. How old is anyone now ??​

Answer 1

let X = father's present age

let Y= Son's age

When I was your age, you were 4 years old."

(y-4) = the difference in their ages

therefore we can write an equation

X - 2(y-4) = 4

X - 2y + 8 = 4

X - 2y = 4 - 8

X = 2y - 4

:

" When I will be 79 you will be my present age."

X= 79 - (y-4)

X = 79 - y + 4

X = 83 - y

Replace X with (2y-4)

2y - 4 = 83 - y

2y+ y= 83 + 4

3y = 87

Y= 87/3

Y = 29 yrs is the son's age

then

83 - 29 = 54 yrs is fathers age

:

:

Check this: 54 - 29 = 25 years is the difference in their ages

When Dad is son's age (29), son will be 4