$4.$ Each year, Data Corporal produces as many as $400$ computers in Boston and $300$ computers in Raleigh. Los Angeles customers must receive $400$ computers, and $300$ computers must be supplied to Austin customers. Producing a computer cost $$800$ in Boston and $$900$ in Raleigh. Computers are transported by plane and may be sent through Chicago. The costs of sending a computer between pairs of cities are shown in the table below. Formulate an MCNFP that can be used to minimize the total $($production distribution$)$ cost of meeting Data Corporal$$s annual demand.