4. (10 Points) An environmentally friendly green home costs about 8% more to construct than a conventional home. Most green homes can save 15% per year on energy expenses to heat and cool the dwelling. For a $350,000 conventional home, how much would have to be saved in energy expenses per year to recoup the difference in initial (construction) costs when the life of the home is 40 years and the discount rate is 7% per year.