4x - y = 9 13x + 4y = -1

Multiply the first equation by 4: 16x - 4y = 36. Add this to the second equation: (16x - 4y) + (13x + 4y) = 36 + (-1), which simplifies to 29x = 35, so x = 35/29. Substitute x back into the first equation: 4(35/29) - y = 9. Solve for y: 140/29 - y = 9, so y = 140/29 - 9 = (140 - 261)/29 = -121/29.