Usually, when you purchase a lot in an auction, you pay not only your winning bid price but also a buyer's premium. At one auction house, the buyer's premium is 21% of the winning bid price for purchases up to $60,000. For larger purchases, the buyers premium is 21% of the first $60,000 plus 7% of the purchase price above $60,000. Express the total purchase price of a lot at this auction house as a function of the final (winning) bid price. Sketch the graph of this function.