the total age of A and B is 12 year more than the total age of B and C. C is how many years younger than A ?  Choose the correct choice
A) 12	B) 24	C) data inadequate	D) none of these	E) 34

Rationale: "solution ( a + b ) - ( b + c ) = 12 ⇔ a - c = 12 . answer a"
Answer: A