Question: If 72 binders can bind 720 books in 22 days, how many binders will be required to bind 660 books in 12 days?

1. 124
2. 120
3. 121
4. 123

Answer: 3. 121

Solution:
workdone for 1 book= (binders x days) / n.o of books=( 22 x72)/720
workdone for 660 books in 12 days for (1 book work)= (binders x 12) /660
(binders x 12) /660=( 22 x72)/720
binders = 121