How do i solve this by using substitution

To solve this using substitution you use what is given to you.

You have both the x and y, however you can choose which one you want to use.

If you choose to use y, then you’ll input the y equation into the x formula

x = 10 -2x -4

Then solve and continue as normal.

If you were to choose x, do the opposite.

y = 10 - 2(y - 4)

Hope this helps!