Help with Accounting Study Guide based on Defered Revenues?

[ChaoticAngel911]

In November and December, 2004, Paul Company, a newly organized magazine
publisher received $60,000 for 1,000 subscriptions (each subscription lasts for 3 years) to
a new monthly magazine at $20 per year, starting with the first issue in March, 2005.
REQUIRED:
Fill in the chart below relating to the amount of revenue to be recorded in each year assuming a year-end of December 31.

Revenue Unearned Revenue at December 31
2004
2005
2006
2007

Answer:

2004 Revenue: $0 Unearned Revenue: $60,000
2005 Revenue: $16,667 Unearned Revenue: $43,333
2006 Revenue: $20,000 Unearned Revenue: $23,333
2007 Revenue: $20,000 Unearned Revenue: $3,333

I do not understand how the study guide came up with the following answers. Can someone please explain? Thank you!

[Joe]

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