However, that doesn't count time answering student questions. That doesn't count office hours. That doesn't count making up homework or tests and grading them.
For me, each class I teach is about 40 hours of work per week. If that is your number, then I got paid about $10 per hour. And I would have been better off at McDonalds as I would have gotten benefits for being full-time.
For those of us who like to teach, this is a Catch-22. It is good for students to have teachers who have been in industry--however, the pay is lousy relative to that same industry. At the same time, I would also be providing cheap labor to the university who should be paying someone a reasonable amount of money.