Question

A can do a piece of work in 14 days while B can do it in 21 days. In how many days they can together finish the work ?

Answer 1

Given, $A$ can do the work in $14$ days.

$B$ can do it in $21$ days.

Let $A$ and $B$ can together complete it in $x$ days.

Therefore,

$\frac{1}{x}=\frac{1}{14}+\frac{1}{21}$

$\frac{1}{x}=\frac{35}{294}$

$x=\frac{294}{35}=8.4$ days

Hence, $A$ and $B$ can together complete the work in $8.4$ days.