The owner of a small construction business needs a new truck. He can buy a diesel truck for $58,000 and it will cost him $0.76 per mile to operate. He can buy a gas engine truck for $53,200, and it will cost him $0.88 per mile to operate. Find the number of miles he must drive before the costs are equal. If he normally keeps a truck for 7 years, which is the better buy?