Need some help with an Algebra problem, please

This formula computes the monthly mortgage payment (principal + interest).

M=P xr/n

1-(1+r/n)^{^-nt}

M-monthly mortgage payment r-annual interest rate n-number of payments per year P-Principal (amount borrowed) t-number of years Write a response that completes the following tasks and meets the list of requirements that follow to build your response for this Critical Thinking Assignment:

First, check if you can use this formula correctly: If you borrow 300,000 at 3.75% annual rate for 30yrs, then mortgage payment (principal + interest) should come out to $1,389.35.

Consider a case where you borrow 235,000 at 3.85% annual rate for 30 years fixed.

1. Compute the mortgage payment using the above formula.
2. Construct the re-payment schedule using Excel. Consider viewing this video for some Excel short-cuts and hints:Repayment Schedule in Excel
3. What is the total payment at the end of 30 years? How much of it is just interest?
4. Now respond to questions 1, 2, and 3, but for a 15-year mortgage.
5. In your opinion, what are the pros and cons of each option (30-year mortgage vs. 15-year mortgage)?