Question

Anil can do a piece of work in $5$ days and Ankur in $4$ days. How long will they take to do the same work, if they work together?​

Answer 1

Step : Find the time required to complete the work

Given :
Time taken by Anil to do the work $=5$ days
Time taken by Ankur to do the work $=4$ days

So,
Amount of work done by Anil in $1$ day $=\frac{1}{5}$

Amount of work done by Ankur in $1$ day $=\frac{1}{4}$

Amount of work done by Anil and Ankur in one day

$=\frac{1}{5}+\frac{1}{4}$

$=\frac{4+5}{20}$

$=\frac{9}{20}$

$\therefore$ Time required to complete the work by Anil and
Ankur $=\frac{1}{\frac{9}{20}}\text{days}$

$=\frac{20}{9}\text{days}$

$=2\frac{2}{9}\text{days}$

Hence, Anil and Ankur together can do the work in
$2\frac{2}{9}\text{days}$.