The ages of sonu and Monu are in the ratio 7 : 5. Ten years hence,

It is given that the ratio of the ages of Sonu and Monu is $7: 5$.

Let the present ages of Sonu and Monu be $7 x$ and $5 x$ years.

After ten years:

Age of Sonu $=7 \mathrm{x}+10$ years

Age of Monu $=5 \mathrm{x}+10$ years

According to the question,

$\frac{7 x+10}{5 x+10}=\frac{9}{7}$

or $49 x+70=45 x+90$

or $49 x-45 x=90-70$

or $4 x=20$

or $x=5$

$\therefore$ Present age of Sonu $=7 \times 5=35$ years.

Present age of Monu $=5 \times 5=25$ years.