The method of substitution depends on the fact that, once you know that two things are equal, you can substitute one any time you see the other and vice versa.
You are given:
That means that any place you see y you can replace it with -2x + 3. A convenient place for us to make this substitution is in your other equation.
is the second equation, and
is the second equation with y replaced by -2x + 3.
Now you have a single 1st degree equation in one variable that can be solved by ordinary means, namely simplification, adding equal things to both sides, and multiplying both sides by equal things.
By the way, I would be very mad at my Mom if she named me 'really confused'.
