12. Реши систему уравнений. { 4x - y = 11, 2x + 3y = 9

From the first equation, y = 4x - 11. Substitute this into the second equation: 2x + 3(4x - 11) = 9. This simplifies to 2x + 12x - 33 = 9, so 14x = 42, which means x = 3. Substitute x = 3 back into y = 4x - 11 to get y = 4(3) - 11 = 12 - 11 = 1. The solution is x = 3, y = 1.