Whats the interest rate of a 7-year, annual $4,000 annuity with present value of $20,000?

Question:

What’s the interest rate of a 7-year, annual $4,000 with present value of $20,000? Annuity
An annuity is a series of equal payment made at equal intervals during a period of time. In other words annuity is a contract between insurer and insurance company in which insurer make a lump-sum payment or a series of payment and, in return,...