Question

A can do a piece of work in 14 dys and b in 21 days a leaves 3 days before the completion of the work

Answer 1

Step-by-step explanation:

They will complete the work in 8.5 days.

Answer 2

$\huge\bigstar\mathfrak\blue{\underline{\underline{SOLUTION:}}}$

If A can do the work in 14 days, his work per day

$\frac{1}{14}$

If B can do the work in 21days, his work per day

$\frac{1}{21}$

If A & B work together, work per day

$= > ( \frac{1}{14} ) + ( \frac{1}{21} ) \\ \\ = > \frac{5}{42}$

Hence, work will be completed, If A & B work together

$= > \frac{42}{5} =( 8 + \frac{2}{5} )days$

If A leaves 3 days before completion of work, hence they worked together for 5 days.

Hence completed work in 5 days

$= > 5 \times ( \frac{5}{42} ) = \frac{25}{42}$

Remaining work

$= > 1 - ( \frac{25}{42} ) \\ \\ = > (\frac{42 - 25}{42} ) \\ \\ = > \frac{17}{42}$

Hence, Number of days required for B to complete

$= > \frac{ \frac{ \frac{17}{42} }{1} }{21} = \frac{17}{42} \times 21 \\ \\ = > \frac{17}{2} = 8.5 \: days$

hope it helps ☺️