If x and y are positive integers for which 3x + y + xy = 115, then what is x + y?
Let 3x + y + xy = 115, x > 0, y > 0 Solving this gives us y = (115 -3x) / (1 + x) So the point is (1, 56) x = 1, y = 56
3 + 56 + 56 = 115
So the answer is x + y = 1 + 56 = 57
