A can finish a job in 10 days and B in 15 days. How many days do they need together?
Q1. A can finish a job in 10 days and B in 15 days. How many days do they need together?
Answer: 6 days
Explanation: Together they do 1/10 plus 1/15 per day, which is 1/6. So they need 6 days.