Janardan completes 2/3 of his work in 10 days. Time he will take to complete of the same 3/5 work, is ?

Answer: Option D

Janardan completes $$\frac{2}{3}$$ of work in 10 days
Janardan completes 1 of work in
$$\begin{array}{rl}& =\frac{10\times 3}{2}\\ & =15\text{ days}\end{array}$$
Janardan completes $$\frac{3}{5}$$ of work in
$$\begin{array}{rl}& =15\times \frac{3}{5}\\ & =9\text{ days}\end{array}$$