.
Substituting into the second equation gives
.
You know so
.
Therefore is the solution.
5x-7=-y
2x-y=0
First, solve one of the equations for one of the variables. It really doesn't matter which equation or which variable. You probably will want to choose the way that's the easiest. I'm going to start by solving the 2nd equation for y:
Now, substitute this into the 1st equation wherever you see a y, and then solve for x:
Now, plug this into the altered version of the 2nd equation:
The answer is (1, 2). You want to try your other example now?
EDIT: Too slow!
OP: Prove It's point is that you have to be careful with notation. Ideally, you should learn LaTeX so that it's not ambiguous when you type . 6/5x is really read as . If you are not using LaTeX and you want to indicate the fraction 6/5 times x, use parentheses: (6/5)x.