Amit can do a task in 10 days and Bhanu can do the same task in 40 days. In how many days will the task be completed if they work together ?

8

We have,

Amit can do a task in 10

Bhanu can do the same task in 40 days

Let the total work = LCM of their timings = 40

Now the efficiency of Amit = 40/10 = 4

And the efficiency of Bhanu = 40/40 = 1

Now they can do the work in = 40/(4+1) = 8