In Gas Pump, South Dakota, Every Buick Owner's Demand for Gasoline

In Gas Pump, South Dakota, every Buick owner's demand for gasoline is 20 - 5p for p less than or equal to 4 and 0 for p > 4. Every Dodge owner's demand is 15 - 3p for p less than or equal to 5 and 0 for p > 5. Suppose that Gas Pump has 100 Buick owners and 100 Dodge owners. If the price of gasoline is $4.50, what is the total amount of gasoline demanded in Gas Pump?

A) 300 gallons
B) 75 gallons
C) 225 gallons
D) 150 gallons
E) none of the above.