the normal force of a certain thing is the weight in force of the object multiplied by the sine function of the angle of inclination, be ∅ in this case. Given the mass of the car equal to 300 slug or 5.17 kg, then the nrmal force is 5.17*9.81 sin ∅ or 50.72 sin ∅. The frictional force is normal force times ∨k or coefficient of friction