Question: A shoemaker has a supply of 100 square feet of type A leather, which is used for soles, 600 square feet of type B leather, used for the rest of the shoe. The average shoe uses 1/4 square feet of type A leather and 1 square foot of type B leather. The average boot uses 1/4 square feet and 3 square feet of types A and B leather, respectively. If shoes sell at $49 a pair and boots at $55 a pair, find the maximum income.