In Financial mathamatics I am having problems determining how long the term of a loan is; the question is pasted below I have to determine how long the loan is for, how do I find this? In order to...

In Financial mathamatics I am having problems determining how long the term of a loan is; the question is pasted below I have to determine how long the loan is for, how do I find this?

In order to plant Christmas trees in another​ field,
Roy signed a note with a face value of ​$
21,000 at a
7​% discount rate. Find the length of the loan in days given that the discount is ​$
408.33. Use​ banker's interest of 360 days.