Had Mukesh been working alone, How many number of days taken by him to complete the task.

Question

Mukesh and Chandan can complete a task in 30 days when working together. After Mukesh and Chandan have been working together for 11 days, Chandan is called away and Mukesh, all by himself completes the task in the next 28 days.

Had Mukesh been working alone, How many number of days taken by him to complete the task.

Answer 1

44.2 days.
They would have needed another 19 days to finish the job together.
Instead Mukesh alone needs 28 days.
So Mukesh works 19/28 of the speed when they work together.
That means he could have done everything in 30*28/19 = 840/19 days (44 days and a bit)

Answer 2

Let's,
Mukesh=A
Chandan=B

(A+B)'s 11 days work=[(1/30)*11]=11/30
Remaining work=[1-(1/30)]=19/30

Now,
(19/30) work is done by A in 28 days
Then whole work will be done by A in [28*(30/19]=840/19
Ans is 840/19 days