Question

A and B can do a piece of work in 15 and 18 days respectively. A worked at it for 10 days and
then B finished the remaining work. Find the time taken by B to finish the remaining work.​

Answer 1

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$\bold{Explanation:}$

A can finish work in 18 days.

It means A can do the work in one day = 1/18 part

B can finish it in 15 days.

It means B can do the work in one day = 1/15 part

B worked alone for 10 days and then left the job

Thus in 10 days B has completed part of work =

1/15 × 10 = 10/15 part or 2/3 part of work

Remaining work left = 1 - 2/3 = 1/3 part of work remaining

A can do 1/18 part in one day

Therefore 1/3 part will be completed by him

= 1/1/18 × 1/3

= 1/3 × 18/1

= 18/3 days

= 6 days

A alone will complete the work in 6 days

Answer : A alone will finish the work in 6 days