How do I solve a system of equations by substitution if both equations equal different variables?

Question

For example,

y=10-2x

x=y-4

Im having a really hard time and if anyone could help me out that would be great

Answer 1

y = 10 - 2x

x = y - 4

So, y = 10 - 2(y - 4)

y = 10 - 2y + 8

3y = 18

y = 6

So, x = y - 4 = 6 - 4 = 2