Please help me Create a situation with an independent and dependent quantity that could match the graph shown

To solve the system of equations below, pedro isolated the variable y in the first equation and then substituted it into the second equation. what was the resulting equation? { 5y=10x {x^2+y^2=36

How is this equation completed? i cannot find any examples in the book.

What is value of x? enter your answer in the box. x =