I need some help calculating amortization for the following question and journalizing the entry.

On Sept 10 2012, Company purchased 2 cash registers on account. Each cost $800 and had a resale value of $1100 each.
They have a useful life of 3 years.
Store furniture ($15000 with $4000 accumulated amortization) and store equipment($20000 with $8000 accumulated amortization) were purchased on Oct 1, 2007.
Furniture have a useful life of 15 years and store equipment have a useful life of 10 years.
Depreciation has not been recorded this year.