Sunrise Swimwear manufactures ladies swimwear in January through June of each year that is sold through retail outlets in March through August. The following table summarizes the monthly production capacity and retail demand (in 1000s), and production and inventory carrying costs (per 1000). Carrying Cost per 1000 Month Capacity Demand Production Cost per 1000 First Month Other Months January 16 — $7,100 $110 $55 February 18 — $7,700 $110 $55 March 20 14 $7,600 $120 $55 April 28 20 $7,800 $135 $55 May 29 26 $7,900 $150 $55 June 36 33 $7,400 $155 $55 July — 28 — — — August — 10 — — — For instance, 1000 units of swimwear made in January to meet demand in April would cost $7,100 in production cost plus $220 in carrying costs during February, March, and April ($110 for carrying into February, $55 for carrying into March, and $55 for carrying into April). a. Draw a network ?ow representation of this problem. b. Implement a spreadsheet model for this problem. c. What is the optimal solution?