2. A retired couple supplements their income by making pie crusts, which they sell to a local grocery store. During September, they produce regular and sweet crusts. The regular crusts are sold for $1.20 per unit, and the sweet crusts are sold for $1.50 per unit. The couple can sell all of the crusts they produce. Flour and sugar are purchased once each month. For September, they have 1,200 cups of sugar and 2,100 cups of flour. Each regular crust requires 1 cups of sugar and 3 cups of flour, and each sweet crust requires 2 cups of sugar and 3 cups of flour. Required: a. Formulate an LP model to determine the number of regular and sweet crusts that will maximize revenues if the couple working together can make a crust of either type in six minutes. They plan to work no more than 60 hours. b. Solve this problem using the graphical solution method. Determine the optimal solution and the amounts of sugar, flour, and time that will be unused.