1.  What must be added to each term of the ratio 7 : 13 so that the ratio becomes 2 : 3 ?
A. 1
B. 2
C. 3
D. 5

Answer: Option D

Explanation:

∵ (7 + N) / (13 + N) = 2/3
⇒ 3(7 +N) = 2(13 + N)
∴ N = 5