national business machines manufactures x model a portable printers and y model b portable printers. each model a costs $100 to make, and each model b costs $150. the profits are $25 for each model a and $45 for each model b portable printer. if the total number of portable printers demanded per month does not exceed 2500 and the company has earmarked no more than $600,000/month for manufacturing costs, what is the optimal profit?