Graph the system of linear equations. Solve the system and interpret your answer.
1. 2x + y = 4, x - y = 2
2. (-x) + y = 1, 3x - 3y = 4
3. 3x - 5y = 7, 2x + y = 9
4. 2x - y = 5, 5x - y = 11
5. (x 3)/4 + (y-1)/3 = 1, 2x - y = 12