Question

P can do a piece of work in 20 days and Q in 25 days. They worked together for 5 days and then Q left the work.
Find the number of days in which P can finish the remaining work.

Answer 1

In 20 days, P can do 1 complete work
In 1 day, P can do 1/20th of the work.
Similarly, Q’s 1 day work=1/25
Therefore, 1 day work of P and Q working together=1/20+1/25=9/100
Therefore, 5 day work of P and Q working together= 9/20
Remaking work=11/20
Number of days required by P to finish the work=(11/20)/(1/20)=11

Answer 2

Answer:

11 days.

Step-by-step explanation:

P does work in 20 days. Q in 25 days.

So, in 1 day P does work = 1/20 ( So, in 20 days it will become 1, that means that his work is done)

Same with Q, 1 day work of Q = 1/25.

The worked together for 5 day.

So, (P + Q)'s 1 day work = 1/20 + 1/25

                                       = 9/100

(P + Q)'s 1*5 day work = 9*5/100 = 9/20.

So, in 5 days 9/20 work was done, remaining work is 1 - 9/20 = 11/20.

Now only P is working.

P's 1*11 day work = 1*11/20

11/20 was the work remaining, which P would do in 11 days.