Question

9. A and B can do a job together in 25 days. After 15 days of working together, together. If A
completes the remaining part of the job in 20 days, how long would each take to complete
the job, working separately?​

Answer 1

Answer:

A and B can do (1/25)th part of the work in a day.

In 15 days that A and B worked together they completed (15/25) or (3/5)th of the work and what remained was (2/5)th of the work.

A completed the (2/5)th part of the work in 20 days. So A would have taken 20/(2/5) = 50 days to complete the work, working alone.

B alone does (1/25)-(1/50) = (1/50)th of the work in a day.

So A and B would both take 50 days to the same work, working alone.

In 15 days A and B did 15[(1/50+(1/50)] = 15X2/50 = 3/5th of the work. and the remaining (2/5) took A (2/5)X50 = 20 days.