A note with a face value 4300 was discounted at 3%. if discount was 21 dollars. find the length of loan in days

The annual discount is 3%, therefore the total discount for 1 year would be:

4300 * 3 : 100 = 129$

Now, you can set a proportion:

discount : annual discount = loan days : days in one year

21 : 129 = x : 360

x = 21 * 360 / 129 = 58.6 days

Hence, the loan duration was 60 days.