Multiply then eliminate

Solve by elimination:

1. 3x + 2y = 12
   2x + 3y = 13
2. 4x - y = 7
   3x + 2y = 18
3. 5x + 3y = 19
   2x + y = 7
4. 7x - 2y = 1
   3x + 4y = 15

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