Question

A can do a piece of work in 20 days and b in 15 days. with help of c, they finish the work in 5




days. in how many days c alone can do the same work?

Answer 1

hope this helps you.....

Answer 2

A can do the work in 20 days

⇒ 1 day = 1/20 of the work

B can do the work in 15 days

⇒ 1 day = 1/15 of the work

Find the amount of work A and B can complete in a day:

1 day = 1/20 + 1/15 = 7/60

Find the amount of work c can complete in a day:

a + b + c can complete the work in 5 days

⇒ 1 day = 1/5 of the work

C alone

⇒ 1 day = 1/5 - 7/60 = 1/12

Find number of days c needs to complete the work:

1/12 of the work = 1 day

12/12 of the work = 1 x 12 = 12 days

Answer: C can complete the work alone in 12 days.