If A and B together can complete a piece of work in 15 days and B alone in 20 days, in how many days can A alone complete the work?

🧠 Explanation (Math):

Given: (A+B) in 15 days; B alone in 20 days; find A alone
Step 1: Rates: A+B = 1/15; B = 1/20
Step 2: A = 1/15 − 1/20 = (4 − 3)/60 = 1/60
Step 3: Time(A) = 60 days
Final Answer: 60