A can do a piece of work in 4 days and B can do it in 12 days. In how many days will they finish the work, both working together:

A can do a piece of work in 4 days and B can do it in 12 days. In how many days will they finish the work, both working together:
Answer: 3 days

A’s rate = 1/4, B’s rate = 1/12 tasks/day. Combined rate = 1/4 + 1/12 = 3/12 + 1/12 = 4/12 = 1/3 tasks/day. Time = 1 ÷ (1/3) = 3 days. Studying this highlights work rate problems, providing lessons on collaborative task planning for efficiency.