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 $131,000 and interest due 3/31/2022. Note B: Dated 7/1/2021, principal of $211,000 and interest at 8% annually, due on 4/1/2022. Frankenstein had accrued a total of $15,900 interest receivable from these notes in its 12/31/2021 balance sheet. The annual interest rate on Note A is closest to: