How much air is needed to fill a ball with a diameter of 7 centimeters

Which graph represents the following piecewise defined function?

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

Solve for x and y: 217x + 131y = 913; 131x + 217y = 827