SSC CPO SI and ASI Model Paper 4

(4) Let the time taken to complete the work by Gabbar alone be X hour.
Work done by Gabbar in one hour $=\frac{1}{\mathit{X}}$
Work done by Jai in one hour = $\frac{1}{\mathit{X}+7}$
Work done by Veeru in one hour = $\frac{1}{\mathit{X}+28}$
According to the question, ⇒ $\frac{1}{\mathit{X}+28}+\frac{1}{\mathit{X}+7}=\frac{1}{\mathit{X}}$
$\Rightarrow \frac{2\mathit{X}35}{\left(\mathit{X}+28\right)\left(\mathit{X}+7\right)}=\frac{1}{\mathit{X}}$
$2{\mathit{X}}^2+35\mathit{X}={\mathit{X}}^2+35\mathit{X}+196$
$\Rightarrow {\mathit{X}}^2=196$
⇒ X = 14