Frankenstein Enterprises received two notes from customers for sales that Frankenstein made in 2016. The notes included: Note A: Dated 5/31/2016, principal of $140,000 and interest due 3/31/2017. Note B: Dated 7/1/2016, principal of $232,000 and interest at 7% annually, due on 4/1/2017. Frankenstein had accrued a total of $16,800 interest receivable from these notes in its 12/31/2016 balance sheet. The annual interest rate on Note A is closest to: