If 2x + y = 7 and x + 2y = 10, then (x + y)/3 =  Answers.
A) 1  B) 4 / 3  C) 17 / 9  D) 18 / 5  E) 4

Rationale: "we have two equations : 2 x + y = 7 x + 2 y = 10 notice that something nice happens when we add them . we get : 3 x + 3 y = 17 divide both sides by 3 to get : x + y = 17 / 3 so , ( x + y ) / 3 = 17 / 9 answer : c"
Answer: C