Solve this word problem?

The cost of purchasing incandescent bulbs for use over a 9750 hour period is $9.75. The energy cost of incandescent bulbs over this period is $73. The cost of one equivalent fluorescent bulb that lasts about 9750 hours is $20. By using a fluorescent bulb instead of incandescent bulbs for 9750 hours, the total savings of purchase price plus energy cost is $46.75. What is the energy cost of using the fluorescent bulb over this period?

The answer is $16.00.

P.S. You might want to consider putting a clue as to what your question is about in the actual question itself as well as the 'extra details' sections so people know what it's about and whether or not they will be able to solve it without clicking on the link, especially people with a slow internet question.