Aman is four times more efficient than Sangram. Aman can complete a work in 45 days less than Sangram. If both of them work together, then in how many days the work will be completed?

Aman is 4 times more efficient than Sangram, so Aman's efficiency: Sangram's efficiency = 4:1. This means if Sangram takes 4x days, Aman takes x days. Given: 4x - x = 45, so 3x = 45, x = 15. Aman takes 15 days, Sangram takes 60 days. Together, their combined rate = 1/15 + 1/60 = 5/60 = 1/12. Working together, they complete the work in 12 days.