Tires for sale

in

I took four tires to a friend's garage sale and was asking $30 a piece. I needed to leave for a few minutes, so I asked him to watch them for me. "Sure," he said, "but if someone offers less, how low are you willing to go?" "Try for more, but I will accept $15," I said, and left. When I returned, my tires were gone. "How much did you get for them?" I asked excitedly. "Fifteen dollars each." "Who bought them?" "I did!"