Question

A can do a peice of work in 25 days
B can do a peice of work in 20 days
How many is required to finish work by A+B​

Answer 1

In context to question asked,

We have to determine the number of days required by A and B together to complete the work.

As per question,

It is given that,

A can do a piece of work in 25 days

B can do a piece of work in 20 days

So, one day work of A will be $=\frac{1}{25} \:unit$

And one day work of B will be $=\frac{1}{20}\:unit$

So, one day work of both A and B will be $=\frac{1}{20} + \frac{1}{25} = \frac{5+4}{100}=\frac{9}{100}$

Hence, time taken to complete the same work by both A and B when they work together will be,

$\frac{1}{\frac{9}{100}}\\=>\frac{100}{9}\\=>11\frac{1}{9}\:days$

Hence, A and B together will complete the work in $11\frac{1}{9}\:days$

Answer 2

Step-by-step explanation:

in 1 day A can do 1/25 part of the work

in 1 day B can do 1/20 part of the work

in 1 day A+B can do (1/25+1/20) =9/100 part of the work

A+B can do 9/100 part of the work in 1 day

they can finish the whole work in 1/9/100=1×100/9 days

=100/9 days