The Harnapps and the Curies are going to the Pizza Palace for dinner. The Harnapps order 3 slices of pizza and 3 colas and have a bill that totals $15. The Curies order 4 slices of pizza and 3 colas and have a bill that totals $18. Determine the best method to solve the system of equations. Then solve the system. 3x 3y = 15 and 4x 3y = 18