Question

Five years ago, $A^{\prime }s$ age was four times the age of $B$. Five years hence, $A^{\prime }s$ age will be the age of $B$. Find their present ages.

Answer 1

Let Present age of A be x and that of B be y.

$x-5=4(y-5)$ .........(1)

$x+5=y+5$ ...........(2)

Subtracting (2) from (1)

$-5-5=4y-20-y-5$

$-10=3y-25$

$15=3y$

$y=5$ .................(3)

Substituting (3) in (2)

$x+5=5+5$

$x=5$

Hence their present ages are 5 years each.