Logan manufacturing wants to mix two fuels, A and B, for its trucks to minimize cost. It needs no fewer than 3000 gallons to run its trucks during the next month. It has a maximum fuel storage capacity of 4000 gallons. There are 2000 gallons of fuel A and 4000 gallons of fuel B available. The mixed fuel must have an octane rating of no less than 80. When fuels are mixed, the amount of fuel obtained is just equal to the sum of the amounts put in. The octane rating is the weighted average of the individual octanes, weighted in proportion to the respective volumes. The following is known: Fuel A has an octane of 90 and costs $1.20 per gallon. Fuel B has an octane of 75 and costs $0.90 per gallon. Formulate and solve the problem using the Excel Solver. What is the minimum cost achieved? Response Feedback: The constraint on octane rating can be written as 90 A/(A+B) + 75 B / (A+B) >= 80 which after some algebra becomes 90 A + 75 B >= 80 A + 80 B, or further, 10 A - 5 B >= 0