Calculate the savings of fuel cost in dollars for one heating season having 5,000 degree days, resulting from the addition of fiberglass insulation to an ordinary insulated 2 x 4 stud wall with ¾ inch of insulating sheating on the outside with an R-value of 2.75, fiberglass insulation 6 inches thick, and a ¾ inch plywood board on the inside. The wall is 30 feet long and 10 feet high. Use a furnace efficiency of 60% and a natural gas cost of $9.00 per million Btu.