If you would like to solve the system of equations, you can do this using the following steps:
x + 4y = 1 ... x = 1 - 4y
2x - 3y = -9
__________
2x - 3y = -9
2 * (1 - 4y) - 3y = -9
2 - 8y - 3y = -9
2 + 9 = 8y + 3y
11 = 11y
y = 1
x = 1 - 4y = 1 - 4 * 1 = 1 - 4 = -3
(x, y) = (-3, 1)
The correct result would be (-3, 1).
