How would you do this on excel?

You've been hired to help people with their mortgage payments for refinancing their house. You are going to calculate for them an effective rate based on their new loan. You'll also need to discuss and create a spreadsheet that calculate the break even point for their new loan. Graph the information and the spreadsheet should also work for different APR for a 30 year loan. Initial loan $450,000 at 4.5% Refinance at 3.75% What is the break even month