How does 12/25 turn into a percent

How can you decide witch operations to use to slice a two step equation

When the solutions to each of the two equations below are graphed in the xy-coordinate plane, the graphs of the solutions intersect at two places. write the y-cordninates of the points of intersection in the boxes below in order from smallest to largest. y=2x y=x^2-3

How do you solving the solution of each system using elimination?