A refinery manufactures two grades of fuel, F1 and F2, by blending four types gasoline, A, B, C, D. Fuel F1 uses gasolines A, B, C, and Din the ratio 1:1:2:4, uel F2 uses the ratio 2:2:1:3. The supply limits for A, B, C, and Dare 1000, 120 00, and 1500 bbl/day respectively. The costs per bbl for gasolines A, B, C, an , are $120, $90, $100, and $150, respectively. Fuels F1 and F2 sell for $200 an 250 per bbl, respectively. The minimum demand for F1 and F2 is 200 and 400 bl/day, respectively. Develop an LP model and determine the optimal roduction mix for F1 and F2.