The perpetual debt instrument can be evaluated using the present value of the expected cash flows.
The expected cash flow from this instrument is a perpetual stream of $800 per year (8% of $10,000). At a market yield of 7%, the present value of this cash flow stream can be calculated as follows:
PV = $800 / 0.07 = $11,428.57
Therefore, the carrying amount of this financial asset would be $11,428.57 and it would be recorded at this amount on the balance sheet. If the market yield changes, the carrying amount of the financial asset would also need to be re-evaluated based on the new yield.