How WP does Mortgage affordability calculation

They’ve created an algorithm to determine what amount the user can afford based on the user’s previous answers. You need that algorithm/equation.

WordPress has nothing to do with how the price is determined…

This is not a question for this forum. It’s a question that you should ask a realtor or a mortgage professional, I’m not sure it’s information that’s going to be easy to find though, as it’s part of the reason why people pay realtors and mortgage professionals to do what they do.