Given the information above, what is the best operating level of prototypes per day for both 3D printers combined?

You are working for a firm that has two 3D printers for creation of simple valve prototypes. Over 24 working days in a given month, the first printer produced 30 prototypes. The second printer, that usually works on a simpler valve prototype, produced 42 prototypes in the same month. During this month the capacity utilization of both 3D printers combined was 75%.

Given the information above, what is the best operating level of prototypes per day for both 3D printers combined?