When the survey results come back employees indicated that the lighting in the building was too low. They are 50 lights in the building. It will cost $50 to replace the light. The new lights are LED lights that are brighter and more efficient and last 10 years. It can save the company $350 per year in energy cost, plus make a brighter more productive work space making employees happier. How many years will it take for the new lights to pay for themselves? (round to the nearest year)