We can solve this system of equations by elimination. Adding the two equations together, we get (x + 2y) + (x - y) = 5 + 2, or 2x + y = 7. Simplifying the first equation, we get x = 5 - 2y. Substituting this into the second equation, we get (5 - 2y) - y = 2, or 3y = 3. Therefore, y = 1.