You are thinking of making your home more energy efficient by replacing some of the light bulbs with compact fluorescent bulbs, and insulating part or all of your exterior walls. each compact fluorescent light bulbs costs $4 and saves you an average of $2 per year in energy costs, and each square foot of wall insulation costs $1 and saves you an average of $.20 per year in energy costs. your home has 60 light fittings and 1100 sq. ft of uninsulated exterior wall. you can spend no more than $1200 and would like to save as much per year in energy costs as possible. how many compact fluorescent light bulbs and how many square feet of insulation should you purchase? how much will you save in energy costs per year?