HELP WITH c.!!!

A electric bill showed 1200 kilowatt hours (kWh) purchased at a cost of $150.00.

a. What does PECO charge per kWh? $0.125

b. An electric dryer is rated at 5400 W. It takes 40 minutes to dry a normal load. What is the cost per load? $0.45

c. Two 100 watt security lights are left on for 8 hours each night. What is the annual electricity cost? $_____

2*100W*8hr/day = 1600 W-hr/day * 365day/yr = 584kWh/yr * $150/1200kWh = $73/yr