Retired auto mechanic hopes to open a proofing shop. Customers would be local new$-$car dealers. Two locations are being considered, one in the center of the city and one on the outskirts. The central city location would involve a fixed monthly cost of $$7,000$ and labor, material, and transportation costs of $$30$ per car. The outside location would have a fixed monthly cost of $$4700$ and labor, material, and transportation costs of $$40$ per car. Dealer price at either location would be $$90$ per car. At what volume of output will the two sites yield the same monthly profit?