Answer:
Lars is paid on a FIXED INTERVAL schedule of reinforcement, and Tom on a FIXED RATIO schedule of reinforcement.
Explanation:
A fixed interval payment schedule refers to being paid after a set amount of time. In this case Lars gets paid an amount every two weeks.
A fixed ratio payment schedule refers to being paid a fixed percent of the total sales made. In this case, Tom is paid a certain commission for every pair of shoes that he sells.