A designer has 12 square feet of cotton, 21 square feet of silk, and 11 square feet of wool. A vest requires 1 square foot of cotton, 2 square feet of silk, and 3 square feet of wool. A purse
requires 2 square feet of cotton, 1 square foot of silk, and 1 square foot of wool. If the purse
sales for $80 and the vest sales for $50, how many purses and vests should be made to
maximize the designer's profit? What is the maximum revenue?