How do you get the linear equation?

Question 1 1 out of 1 points A service company would like to develop a model that will help allocate their technicians' time between service calls to "regular customers" and "new V customers". The company wants to maximise the number of hours spent with customers each week. A maximum of 80 hours of technician time is available per week. The technician time spent on new customers must be at least 60% of the total time spent on all the customers. Let R and N be the number of hours spent with regular and new customers respectively