Cooper runs a farm stand that sells apples and grapes. Each pound of apples sells for $3 and each pound of grapes sells for $2.25. Cooper sold 3 times as many pounds of apples as pounds of grapes and he made $180 altogether. Graphically solve a system of equations in order to determine the number of pounds of apples sold, x, x, and the number of pounds of grapes sold, yy.