What must be added to each term of the ratio 2 : 3, so that it may become equal to 4 : 5? Choose the correct choice from the following answers:
A) 2  B) 4  C) 6  D) 9  E) 8

Rationale: let the number to be added be x , then ( 2 + x ) : ( 3 + x ) = 4 : 5 ⇒ ( 2 + x ) / ( 5 + x ) = 4 / 5 5 ( 2 + x ) = 4 ( 3 + x ) 10 + 5 x = 12 + 4 x 5 x - 4 x = 12 - 10 x = 2 answer : 2
Answer: A