The present ages of two girls are in the ratio 3 : 5. Five years hence, the ratio of their ages will be 2 : 3. Find the present age of the younger girl.
Solution
Let the present ages of the two girls be 3x years and 6x years
From the data,
$\left( 3x+5 \right):\left( 5x+5 \right)=2:3$
$\Rightarrow 9x+15=10x+10$
$\Rightarrow x=5$
$\therefore $the present age of the younger girl is $3x=3\times 5=15$ years.