What is the respective ratio between total number of books purchased for libraries A and B together in 2003 and total number of books purchased for the same libraries together in 2007?
A) 22: 31
B) 21: 31
C) 11: 17
D) 11: 19
E) 22: 35
Correct Answer: A
$ \therefore $ Required ratio $ =\frac{880}{1240}=\frac{22}{31}or22:31 $