The total age of A and B is 18 years more than the total age of B and C. C is how many years younger than A ?  Select:  A) 12  B) 27  C) 21  D) 18  E) 11

Rationale: ( a + b ) - ( b + c ) = 18 a - c = 18 . c is younger than a by 18 years . answer : d
Answer: D