Ajay can do a piece of work in 25 days and Sanjay can finish it in 20 days. They work together for 5 days and then Ajay goes away. In how many days will Sanjay finish the remaining work?

Ajay' s 1 days work = 1/25
Similarly, sanjay's 1 days work = 1/20
Ajays and Sanjay 's together 1 day's work
= (1/25) + (1/20) = (4 + 5)/100 = 9/100
Their 5 day's work together
= 5 x 1 day's work
= 5 x (9/100) = 45/100
Remaining work = 1 - (5/100) = 55/100
Now, this remaining work is done by Sanjay.
Let Sanjay takes N days to complete it.
Then, (1/20) x N = 55/100
⇒ N = (55 x 20)/100
∴ N = 11 days
So, remaining work is done in 11 days by Sanjay.