Question

A and B take 6hours and 9hours respectively to complete work three work togather

Answer 1

Time taken by A to complete the work = 6hrs.

Work done by A in 1 hr. = 1/6.

Time taken by B to complete the work = 9days .

Work done by B in 1 day = 1/9.

Therefore work done by (A + B) in one day = 1/6 + 1/9 = 3+2/18=5/18.

Therefore time taken by A+B to complete the work = 18/5 = ${3 \:3/5}$days

Answer 2

In one hour A completes=1/6 part of the work

In one hour B completes =1/9 part of the work

In one hour they together complete = {(1/6)+(1/9)}

                                                             = (6+4)/36

                                                             = 10/36

                                                             = 5/18 part of the work

5/8 part of the work is completed in 1 hour

So, 1 part of the work is completed in = 8/5

                                                               =1+(3/5) hours

So, they together completes the work in 1 whole of 3/5 hours.