Question

A can do a piece of work in 15 days while B alone can do it in 20 days. They worked together for 3 days then A left the work. In how many days will B finish the remaining work?​

Answer 1

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A can do a work in 15 days and B in 20 days.

The part of work done by A in 1 day = 1/15

The part of work done by B in 1 day = 1/20

So, the part of work done by A and B together in 1 day = (1/15) + (1/20) = 7/60

Then, the part of work done by them together in 6 day = (7/60) × 6 = 7/10

So, the remaining part of work = 1 - (7/10) = 3/10

∴ The fraction of work left = 3/10..