A local defense contractor is considering the production of fireworks as a way to reduce dependence on the military. The variable cost per unit is $40D. The fixed cost that can be allocated to the production of fireworks is negligible. The price charged per unit will be determined by the equation p equals $ 328 minus 9 Upper D, where D represents demand in units sold per week.   a. What is the optimum number of units the defense contractor should produce in order to maximize profit per week? b. What is the profit if the optimum number of units are produced?