An appliance dealer wants to purchase a combined total of no more than 100 refrigerators and dishwashers for inventory. Refrigerators weigh 100 pounds each. Suppose that the dealer is limited to a total of 12,000 pounds. She also wants to have at least as many refrigerators as dishwashers. If a profit of $35 for each refrigerator and $20 on each dishwasher, how many of each should be purchased and sold to make the largest profit