Consider a problem in which a car of mass m is on a road tilted at an angle θ. the normal force

The first thing you must do to find the normal force is to know that it is always perpendicular to the surface.
 The weight always points down.
 Making a free body diagram in vertical direction we have that the normal force is:
 N = m * g * cosθ
 answer:
 the normal force is:
 N = m * g * cosθ