Hi Matt,

I'd be happy to help you with your Excel calculations!

To calculate the total interest earned over the life of the loan, you can use the following formula:

=total interest paid - principal

To calculate the total interest paid, you can use the following formula:

=IPMT(APR/12, number of months, principal)

To calculate the monthly payment for your client, you can use the PMT function. However, if you're getting a negative number, it's likely because you need to include a negative sign before the principal amount. Here's the correct formula:

=PMT(APR/12, number of months, -principal)

Just make sure to replace "APR," "number of months," and "principal" with the appropriate cell references in your spreadsheet.

1. Open the Excel file.
2. Click on the cell where you want to display the monthly payment.
3. Type the formula =PMT(APR/12, number of months, -principal) and press Enter.

Best,
[Your Name]