A and B can complete a work in 12 days. B and C can complete the same work in 18 days. C and A can complete in 24 days. How many days will take for A, B and C combined together to complete the same amount of work?

1/a+1/b = 1/12 1/b+1/c = 1/18 1/c+1/a = 1/24

so 2(1/a+1/b+1/c) = (6+4+3)/72 or 1/a+1/b+1/c = 13/(2*72)

or A , B and C together can finish in 144/13 or 11.1 days.

a+b=12 b+c=18 c+a=24 a+b+c=(12+18+24)/2 = 27

P is able to do a piece of work in 15 days and Q can do the same work in 10 days. If they can work together for 2 days, what is the fraction of work left?

If 15 men take 21 days of 8 hours each to do a piece of work. How many days of 6 hours each would 21 women take, if 3 women do as much work as 2 men?