12) Aarti can do a task in 40 days, and Bhavna in 30 days. If they work together for 10 days, how much work is left?
Aarti’s 1-day work = 1/40, Bhavna’s 1-day work = 1/30.
Together, 1-day work = 1/40 + 1/30 = 7/120.
Work done in 10 days = 10 × 7/120 = 7/12.
Remaining work = 1 - 7/12 = 5/12.