Rectangle A has sides a and b, and rectangle B has sides c and d. If a/c=b/d=3/4, what is the ratio of rectangle A’s area to rectangle B’s area? Choose the correct option:
A) 3 / 4  B) 9 / 16  C) 16 / 3  D) 4 / 3  E) 3 / 16

Rationale: "the area of rectangle a is ab . c = 4 a / 3 and d = 4 b / 3 . the area of rectangle b is cd = 16 ab / 9 . the ratio of rectangle a ' s area to rectangle b ' s area is ab / ( 16 ab / 9 ) = 9 / 16 . the answer is b ."
Answer: B