Question

300men can do piece of work in 16 days .how many men would do 1/5 of the work in 15 days?

Answer 1

100% of the work -- 16 days -- 300 men
20% of the work -- 15 days -- x men

x = 20/100 × 16/15 × 300
= 64 men

Answer 2

I assume work done is same by every man
300 men can do a work in 16 days
so each day they finish $\frac{1}{16}$ part of work
So each day a man does $\frac{1}{300*16}$ part of work
Let x workers do $\frac{1}{5}$ th work in 15 days
So work done by x workers in 15 days is$\frac{15x}{300*16} = \frac{1}{5}$
$x = \frac{20*16}{5} = 64$
So we need 64 workers