Final answer:
Chuck Sox and his three employees have a productivity of 4 boxes per hour.
Step-by-step explanation:
The productivity of Chuck Sox and his three employees can be calculated by dividing the total number of boxes they make by the total number of hours they work. In this case, they make 120 boxes in 30 hours. To calculate their productivity, we can divide 120 boxes by 30 hours, which equals 4 boxes per hour. Therefore, their productivity is 4 boxes per hour.