pls help

Demand for a certain kind of SUV obeys the following equation, D(x,y) = 23,000 1y 11(0.8y 10)*? where x 1s the price per car in dollars, y is the cost of gasoline per litre, and D is the number of cars. Suppose that the price of the car and the price of gasoline 7 vears from now obey the following equations: x = 67,200+ 1007, y=138+ 14\\]? What will the rate of change of the demand be (with respect to time) 2 years from now