Solve for x: x²+7x+45=0​

What is the name used to describe a graph where for some value of x, there exists 2 or more different values of y?

We just started the introduction into circles and i have no idea how to do this.

Gabriel determined that his total cost would be represented by 2.5x + 2y – 2. his sister states that the expression should be x + x + 0.5x + y + y – 2. who is correct? explain.