Question

a can do a piece of work in 12 days B can do the same work in 15 days a ABC together can finish the work in 5 days how many days will c alone complete the work

Answer 1

a's 1 day work = 1/12
b's 1 day work =1/15
abc's 1 day work =1/5
1/12+1/15-1/5
take lcm=60
3/60
=20 days