can someone correct this for me please.

Question

Directions: Solve the system by substitution.

x + y = 12
y = 2x

this is what i did:

in the first equation i substituted y for what i have in the second equation so now it looks like this:

x +2x = 12
3x = 12
x = 4

now i substitute my x into the first equation to look like this:

4 + y = 12
y = 8

so the answer is for variable x its 4
for variable y is 8

right!

thank you.