Solve by adding or subtracting

Solve by elimination:

1. 3x + y = 10
   2x - y = 5
2. 4x + 3y = 17
   4x - 2y = 7
3. 5x + 2y = 14
   3x + 2y = 10
4. 6x - 5y = 4
   2x + 5y = 20

Submit Exercise