Question

Mary is twice older than her sister. In $5$ years time, she will be $2$ years older than her sister. Find how old are they both now.

Answer 1

Let age of mary =$m$

Let age of her sister =$s$

Given that, $m=2s$

After $5$ years, mary will be $2$ years older than her sister.

$(m+5)=(s+5)+2$

$\therefore m=s+2$

$m=2s\Rightarrow s+2=2s\Rightarrow s=2$

$\therefore m=4$

Mary is $4$ years old and her sister is $2$ years old.