Low-energy lightbulbs typically cost $3.95, have a life of nine years, and use about $2.05 of electricity a year. Conventional lightbulbs are cheaper to buy, for they cost only $0.59. On the other hand, they last only about a year and use about $7.05 of energy. (Use PV table.) a. If the real discount rate is 6%, what is the equivalent annual cost of the two products?