UNsolve 2 variable linear equations & inequalities

The solution of a linear equation in 2 variables, f(x,y) = 0, is a straight line in the x,y plane. The solution of a linear inequality is EITHER all the points above that line or below it. To UNsolve a linear equation or inequality, use the a, b and c sliders in the rightmost panel to fix the solution set. The left panel will show the solution set. The center panel will show you a linear equation or inequality that has that solution set. You can use the c slider in the rightmost panel to see other linear equations or inequalities that have the same solution set. For a given solution set, how many equations or inequalities are there that have that solution set? How do you know? Can you prove it?