A businessman is considering opening a small specialized trucking firm. To meet the firm's suppliers' demand require- ments, it is estimated that it must have a daily trucking capacity of at least \( 84,000 \) cubic ft. Two types of trucks are appropriate for the specialized operation. Their characteristics and costs are summarized in the table below. Out of all the potential drivers, \( 40 \) drivers must be employed and at least \( 15 \) trucks must leave the facilities. The businessman's objective is to minimize the total cost outlay for trucks.
(a) Formulate a linear programming model in standard form for this scenario, defining all variables used. Graph the constraints below.