plz show the steps, not the excel, thx

There is a bond on a company's books with an original term of 10 years that was purchased for a premium at its issuance, just over 2 years ago. The bond pays semi-annual interest. With the receipt of the latest coupon, the corresponding amount for amortization of the premium was $218.55. Exactly one year ago, the amount for amortization of the premium was $206.00. Based on the relation between subsequent amounts for amortization of the principal, what was the original value of the preminum? Answer correct to 2 decimals