First data: A and B working separately do work in 9 and 12 days

Second data: if they do work in alternately.

1 day is A

2 day is B

3. day is A …………………. Like that

If they do work like that in how many days they finish.

A is one day work =1/9

B is one day work =1/12

If A and B is working together alternately then there work in two days=1/9+1/12=7/36

Why add 2 days mean firs day A work then second day B is working so I mention two days

These is very important step so observe carefully

There two days work is 7/36 if they are finish work then there ratio is 36/36 which mean 1 fulfill work complete work.

So x*7/36 is <36/36 style="font-weight: bold;"> 5. So 5*7/36=35/36 so they are complete 35/36 Remaining work is 1-35/36=1/36 One day work* days= total work 11 day work is A’ duty . A is one day work is 1/9 Days=? Total work=1/36 Days=total work/one day work= (1/36)*9=1/4 Total time =10+1/4= 10¼ (10 days and one half day) work in(5*2(a and b work alternatively so I give 2)=10) days Reference form R.S Aggarwal Book