Question

if 30 men do1/7 of a job in 2 days how many days will 21 men take do do job

Answer 1

According to the question :-

30 men do ${^1/_7}^{th}$ of job in 2 days.
$\therefore$ 30 men do the job in 2 × 7 = 14 days.
$\therefore$ 1 men do the job in 30 × 14 days
$\therefore$ 21 men do the job in $\frac{30\times14}{21}$

$=\frac{30\times\cancel{14}^2}{\cancel{21}_3}$ days

$=\frac{^{10}\cancel{30}\times2}{\cancel{3}_1}$ days

$=20$ days