5. The price of a gallon of gasoline has decreased from $15.00 to $12.00. What is the percentage decrease?

To calculate the percentage decrease, you can use the following formula:

percentage decrease = ((original value - new value) / original value) x 100

Using this formula and plugging in the values given in the question, we get:

((15 - 12) / 15) x 100 = 20%

Therefore, the percentage decrease in the price of gasoline is 20%.