A light fixture at a traffic intersection operates on exactly 500 watts of power to light the bulbs on the fixture. Any combination of 125-watt, 100-watt, 75-watt or 60-watt light bulbs can be used, but the total number of watts must be 500. More than one of the same watt can be used. How many combinations could be used if at least one bulb must be a 60-watt?
