A can do a work in 30 days and B can complete the same work in 45 days. In how many days the work will be completed if both work together?
Answer: D
A completes the work in 30 days. A's one day work will be 1/30 of the work. B's one day work will be 1/45 of the work.
Both work together, in one day, 1/30 + 1/45 of the work will get over.
In one day 75/1350 of the work will get over. Which means the work will get over in 1350/75 days. The work will get completed in 18 days.