Answer: x = -6, and y = -6 (-6, -6)
Step-by-step explanation: What we have here is a pair of simultaneous equations. Since we have been instructed to solve by substitution, we shall begin with the one which has one of the variables as having a coefficient of 1. We shall start with equation 2 which is,
y = 2x + 6
Having taken note of this, we can now go on to the other equation and substitute for the value of y.
Hence, from equation 1,
4x - 4y = 0 (substitute for the value of y)
4x - 4(2x + 6) = 0
4x - 8x - 24 = 0
-4x -24 = 0
Add 24 to both sides of the equation
-4x = 24
Divide both sides of the equation by -4
x = -6
Having calculated the value of x, we can now go on to substitute for the value of x in equation 2.
Therefore,
y = 2x + 6
y = 2(-6) + 6
y = -12 + 6
y = -6.
So, x = -6 and y = -6
