Solve the system by substitution

Answer:
-2
Step-by-step explanation:
[tex]y = - 6x \\ y = - 4x + 4 \\ then \: substitute \\ - 6x = - 4x + 4 \\ - 6x + 4x = 4 \\ - 2x = 4 \\ \frac{ - 2x}{ - 2} = \frac{4}{ - 2} \\ then \: - 2 \: cancel \: by \: - 2 \\ x = - 2[/tex]