If 2x + y = 7 and x + 2y = 8, then (x + y)/3 = Choose the correct choice from the following.
A) 1  B) 4 / 3  C) 17 / 5  D) 18 / 5  E) 5 / 3

Rationale: "we have two equations : 2 x + y = 7 x + 2 y = 8 notice that something nice happens when we add them . we get : 3 x + 3 y = 15 divide both sides by 3 to get : x + y = 5 so , ( x + y ) / 3 = 5 / 3 answer : e"
Answer: E