Question: You purchase an ancient Egyptian medallion at the State Fair from a vendor who swears it is pure gold. The medallion weighs 859.4 grams and its volume in cubic centimeters is 52. You suspect that the medallion is actually a mixture of copper and gold. You know that copper weighs 9 grams per cubic centimeter and that gold weighs 19.3 grams per cubic centimeter. Set up and solve a system of equations to find the percentage of copper by volume in the medallion.