substitution matrix

Two grocery stores publish the sale prices for various canned foods including beans, corn, peas, and tomatoes. The prices per can that store 1 charges are 48 cents for beans, 40 cents for corn, 46 cents for peas, and 64 cents for tomatoes. At store II the corresponding prices, for the same size cans as in store I are 50 cents, 37 cents, 48 cents and 60 cents. A shopper plans to purchase 6 cans of beans, 10 cans of corn, 8 cans of peas, and 9 cans of tomatoes.
(a) Let A be the 1 x 4 matrix that gives the quantity of each vegetable in alphabetical order, and let C be an appropriate cost matrix containing the prices for each store. Show both A and C.
(b) Find AC and explain what the entries in AC represent.

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substitution matrix