It’s simple really, the answer is x = -4
y = -2/3x
So we plug in y = -2/3x for the value of y in the equation we need to solve.
4x - 9(-2/3x) = -40 (9 • -2/3x = -6x)
4x - (-6x) = -40 Multiply together
4x + 6x = -40 Combine like terms
10x = -40 Isolate x
x = -4
