You should always make both equations equal to 1 variable, you can choose.
I’m gonna do y.
FIRST EQUATION:
2x + y = 9
y = 9 - 2x
SECOND EQUATION:
8x + 4y = 36
4y = 36 - 8x
y = 9 - 2x
Now, since both equations are equal to y, we can equal them to each other.
9 - 2x = 9 - 2x
Since both sides are the same, this means that the equations are the exact same, meaning that there are infinite solutions.
This is because if you graphed them, the lines would just look like 1 line because they are the same.
