If (A+B) = 12, (B+C) = 9 and (C+D) = 3, what is the value of (A+D)?	Choose one:  A) 16 .  B) 8 .  C) 7 .  D) 6 .  E) - 2 .

Rationale: "given a + b = 12 = > a = 12 - b - - > eq 1 b + c = 9 c + d = 3 = > d = 3 - c - - > eq 2 then eqs 1 + 2 = > a + d = 12 - b + 3 - c = > 15 - ( b + c ) = > 15 - 9 = 6 . option d . . ."
Answer: D