Frankenstein Enterprises received two notes from customers for sales that Frankenstein made in 2021. The notes included:
Note A: Dated 5/31/2021, principal of $128,000 and interest due 3/31/2022.
Note B: Dated 7/1/2021, principal of $215,000 and interest at 9% annually, due on 4/1/2022.
Frankenstein had accrued a total of $15,600 interest receivable from these notes in its 12/31/2021 balance sheet.
The annual interest rate on Note A is closest to: