Can you break down the solution for me for this math problem: Florida is starting a promotion where every car that arrives gets one orange per passenger. A family of 4 arrives and gets their oranges. They had planned to stop for a snack later where they would spend $15 in total, but now that they have the oranges they don't have to buy them at the stop. When they get to the stop they see that the oranges would've cost $1.5 each. What percentage of the money they planned to spend did they save instead?