A stereo store sells three brands of stereo systems, brands A, B, and C. It can sell a total of 100 stereo systems per month. Brands A, B, and C take up, respectively, 5, 4, and 4 cubic feet of warehouse space, and a maximum of 480 cubic feet of warehouse space is available. Brands A, B, and C generate sales commissions of $40, $20, and $30, respectively, and $3200 is available to pay the sales commissions. The profit generated from the sale of each brand is $70, $210, and $140, respectively. How many of each brand of stereo system should be sold to maximize the profit?