In an average day, John's household uses 20kWh of electricity. If the cost of electricity is $0.10 per kilowatt-hour, approximate the amount John will need to pay for the electricity his household uses in one year. (*Round your answer to the nearest dollar and assume 365 days in a year) In one year, how many trees will Joe's system do the work for if his system produces 4000kWh of power in that year? Make the following assumptions: 1 tree can absorb approximately 13 pounds of CO2 in one year, each kilowatt-hour of energy saved keeps 1.9 pounds of CO2 out of the air. (*round your answer to the nearest tree)

If Joe is installing a PV system at his home. The cost for 10 solar panels is $9000.00. For mounting hardware, wiring and installation, Joe figures he must add an additional 45% of the cost of the solar panels. How much does Joe expect his total system cost to be?

If The total cost of Joe's PV system is $12,000.00 and he will save approximately $80.00 per month on his electric bill, how many months of savings will be required before Joe has earned his entire investment back? (*round answer to the nearest month and assume the Joe's electricity usage and his electricity cost remain constant)