An incident ray strikes a mirror with an angle of 20 degrees relative to the normal of the mirror. What is the angle of the reflected ray?

An incident ray strikes a mirror with an angle of 20 degrees relative to the normal of the mirror. What is the angle of the reflected ray?

Here is an image showing the angle descriptions:  http://study.com/cimages/multimages/16/angle_of_reflection_1b.png