An insulation plant makes two types of insulation called type B and type R. Both types of insulation are produced using the same machine. The machine can produce any mix of output, as long as the total weight is no more than 70 tons per day. Insulation leaves the plant in trucks; the loading facilities can handle up to 30 trucks per day. One truckload of type B insulation weighs 1.4 tons; one truckload of type R weighs 2.8 tons Each truck can carry type B insulation, type R insulation, or any mixture thereof. The insulation contains a flame retarding agent which is presently in short supply; the plant can obtain at most 65 canisters of the agent per day. One truckload of (finished) type B insulation requires an input of three canisters of the agent, but one truckload of type R insulation requires only one canister. Carla Linton, the plant manager, has calculated that, at current prices, the contribution from each truckload of type B is $950, and $1,200 for type R. There appears to be no difficulty in selling the entire output of the plant, no matter what production mix is selected. How much of each kind of insulation should be produced? Formulate the problem of determining the optimal number of truckloads of types B and R and use the Excel solver to obtain a solution.