Complete the Car class shown below. A Car has a fuel tank level, and a miles-per-gallon value. Assume that all cars have 12-gallon gas tanks. public class Car
{
// declare your constants and instance variables here

// postcondition: all instance variables are initialized
public Car(double mpgValue, double gallons)
{

}

// postcondition: the fuel level is increased by the amount given by the parameter
public void addFuel(double gallons)
{

}

// postcondition: the fuel tank level is decreased by the amount of gas
// that it would take this Car to drive the number of miles given by the parameter
// The fuel level cannot be negative.
public void drive(double miles)
{

}

// other methods not shown
}