A and B can do a piece of work in 4 days, while C and D can do the same work in 12 days. In how many days will A, B, C and D do it together?

Question: A and B can do a piece of work in 4 days, while C and D can do the same work in 12 days. In how many days will A, B, C and D do it together?Solution:A and B can do a piece of work in 4 daysIn 1 day A and B can do 1/4 part of workC and D can do the same work in 12 daysIn 1 day C and D can do 1/12 part of workIn 1 day A, B, C and D will do = 1/4 + 1/12 = (3 + 1)/12 = 4/12 = 1/3∴ A, B, C and D will together take 3 days to complete the work.