Interest Rate on seller carry back

What would be the fair interest rate to offer a seller who is willing to do a 25% second in an apartment building?

Your focus should be more on what makes sense for you and the deal. Run multiple scenarios with varying interest rates with the lowest interest rate as your best and the highest interest rate as the most you’re willing to pay. This will give you the range with which to begin your negotiations with the seller.

Thank you so much that was very helpful.