Please explain in details

A loading company based in Halifax seeks to develop an employee schedule for a period of 16 hours. Employees are classified into three skill levels (A, B, and C) with hourly wages of $40, $25, and $15 respectively. There are two types of working shifts: 4 continuous hours for part-time employees and 8 continuous hours for full-time employees. Part-time employees are all classified into skill level C and Full-time employees are classified into skill level A or B. The expected loading requirements for each time period of the day are listed below. Shifts Time Periods Cases to be loaded 1 2 3 4 07:00 11:00 11:00 15:00 15:00 - 19:00 19:00 - 23:00 400 200 250 300 Each employee with skill level A can load 30 cases per hour, those with skill level B can load 20 cases per hour and those with skill level C can load 10 cases per hour. It is recommended that the total number of part-time employees not be over 30 percent of full-time em- ployees in each shift. In addition, it is required that at least 25 percent of the total number of employees must be classified as skill level A. Formulate an LP model to determine the optimal number of employees required at each time period (shift) to minimize the overall costs and meet the loading requirements