I need help figuring out simple interest and the balance of an account. Example P = $525, r = 6%, t + 9 years

Question

I need help figuring out simple interest and the balance of an account.  Example P = $525, r = 6%, t + 9 years

helper · Answer

The formula for simple interest is, I = PRT (Interest = Principle * Rate * Time) Balance of account ? t + 9 years?

tia · Answer

two sums of money totaling 15000 earn 5% and 7% annual interest. if the total interest from both investments amounts to $870, how much is invested at each rate?