Math help (woozie help please!)

[Saga]

Alright, I need to find the amount of money one would save using a 75-watt soft white normal bulb as opposed to an 18-watt fluorescent. Here's the data I have so far:

Appliances account for 64.7% of electricity consumption in the average American household (2001). Refrigerators consumed the most electricity (14%), followed by lighting (9%).

18-watt fluorescent: $6 - 20,000 hrs life
75-watt soft white normal bulb: $3-4 - 2,000 hrs life
Average price of electricity in U.S. in 2008 is 11 cents/kilowatt hour.

Using a 75-watt soft white normal bulb, generating .075/kw-hr, you would get 121 hours of light for $1.
Using a 18-watt fluorescent light bulb, generating .018/kw-hr, you would get 505 hours of light for $1.

For $10, 75-watt soft white normal gets 1,210 hours of light.
For $2, 18-watt fluorescent gets 1,010 hours of light (near equivalent).

For the average household using 600 kilowatt-hours of electricity a month, the total bill would be $84.80 (as of October 2008). Roughly 10% of that electricity is lighting, so $8.40 dedicated to light bulbs. For 75-watt soft white, you'd get 1,016 hours of lightning with that $8.40. For 18-watt fluorescent, you would get 4,242 hours of light.

Where the hell do I go from here to figure out a difference in cost? Assuming the $8.40 is used for 75-watt fluorescent, how do I figure out how much I save using an 18-watt fluorescent?

Edit: figured it out, nevermind. Shouldn't have been using the $8.40, I should have been using 60 kWh as the 10% of electricity for lightning. So it came out to...$4.50/month using 75-watt soft white normal bulbs and $1.08/month using 18-watt fluorescent, for a savings of $3.42/month.

[Klutz]

Fuck that. General Studies major with a lean in Science ftw.

[Demosthenes11]

E. Too much information