A and B working together can do a piece of work in 12 days, B and C can do it in 15 days nd C and A can do the same work in 20 days b. How long would each of them take to complete the job?

Explanation

Work done by A and B in 1 day `=(1)/(12)`
Work done by B and C in 1 day=`(1)/(15)`
Work done by C and A in 1 day=`(1)/(20)`
adding all the three, we get the work dne by `(2A+B+C)` in day `=(1)/(12)+(1)/(15)+(1)/(20)=(1)/(5)`
`:.` A, B C can together finish `(1)/(10)` of the work in 1 day
`:.` Work done by A in 1 day
= Work done by A, B and C in 1 day- Work done by B and C in 1 day.
`=(1)/(10)-(1)/(15)-(1)/(30)`
`:.` a alone can do it in 30 days.
Work done by B in 1 day `=(1)/(10)-(1)/(20)-(1)/(20)`
`:.` B alone can do in 20 days.
Work done by C in 1 day `=(1)/(10)-(1)/(12)-(1)/(60)`
`:.` C alone can do it in 60 days.