Jim can fill a pool carrying buckets of water in 30 minutes. Sue can do the same job in 45 minutes. Tony
can do the same job in 1 . hours. How quickly can all three fill the pool together?

The electric company charges 3 cents per kilowatt-hour. George used 2800 kilowatt-hours in April, 3200
kilowatt-hours in May, and 3600 kilowatt-hours in June. What was his average cost of electricity for the 3
months?