SSC CHSL 17 Mar 2020 Shift 2 Paper

Let the present age of Aarav $=\mathit{x}$ yr
and Aarav's mother's age $=\mathit{y}\mathrm{yr}$
According to the question,
$\mathit{y}=3\left(\mathit{x}-5\right)$
$\mathit{y}=3\mathit{x}-15$
$3\mathit{x}-\mathit{y}=15$ ...(i)
$\mathit{y}+5=2\left(\mathit{x}+5\right)$
$\mathit{y}+5=2\mathit{x}+10$
$2\mathit{x}-\mathit{y}=-5$ ...(ii)
Subtracting Eq. (ii) by Eq. (i), we get
$\mathit{x}=20\mathrm{yr}$
Hence, Aarav is $20\mathrm{yr}$ old.