You are given 3 equations up front. If you take the first 2 equations and set them equal to each other, this accomplishes two things: first, doing this eliminates the variable y, and second, if the graphs of the first 2 equations intersect, at the point of intersection the y-value of one must equal the y-value of the other.
The third equation is easier to solve, because the variable y has been eliminated, leaving only x as variable.
Please take a look at the remainder of this question and see what you yourself are able to do. Share your work. Then, if you'd message me, I'd be glad to take another look and give you suggestions.