Could use some help with the following Discrete Mathematics question.

Given the following:

She is a Math Major or a Computer Science Major.

If she does not know discrete math, she is not a Math Major.

If she knows discrete math, she is smart.

She is not a Computer Science Major.

Therefore, she is smart.

Prove that this argument is valid using predicate logic and rules of inference. Construct your proof in steps.

Step Justification