Mason is getting quotes from two different landscaping companies to put river rock along one side of his house at a depth of 0.5 foot. The surface area of the space he wishes to install rock in is rectangular and has a length that is eight times its width. The first company charges $3.50 per cubic foot of rock and $80 for delivery. The second company charges $2.50 per cubic foot of rock and $120 for delivery. Which system of equations can be used to determine the value of the width, x, at which the cost of the two companies, y, is the same?