The answer would look something like this:

There could also have a simplified version.
I hope this helps.
The top one is the answer
Answer:
it has one solution
Step-by-step explanation:
1.y=x-3
2. 3y-3x sub x-3 in place of y therefore
it can also be written as 3x-3x-9=9
if you add 9 to both sides 3x-3x-9+9=-9+9
0+0=0
Answer:
See below.
Step-by-step explanation:

Distribute:

Answer:
The 3rd one
Step-by-step explanation: