Question

A can do a piece of work in 1 day while B does it in 10 days. How long will they take to do it together?

Answer 1

Answer: Correct  

A can do piece of work in 15 days.

B can do piece of work in 10 days.

then together they can do it in x days.

x

1

​

=  

15

1

​

+  

10

1

​

 

x

1

​

=  

30

3+2

​

=  

6

1

​

 

x=6 days. together they can do work in 6 days.

Step-by-step explanation:

Answer 2

Let B alone take x days to do the work.

since A alone can complete the work in 15 days.

• In one day A completes 1/15th part of the work.

similarly, in one day B completes 1/xth part of the work.

A and B together completes 1/10th part of the work in one day.

Now A's one day's, work + B's one day's work

$\frac{1}{15} + \frac{1}{x} = \frac{1}{10}$

$\frac{1}{x} = \frac{1}{10} - \frac{1}{15} = \frac{15 - 10}{150} = \frac{1}{30}$

$x = 30 \: days$

B can alone do the work in 30 days.