I am trying to find out how much principal I would be required to pay down to meet a DSCR test. So, if I know my NOI is $1M and my required coverage is 1.10x, then I have a total payment (P&I) of $909,090. How can I solve for the principal balance that would give me a total payment of $909k during that period?

My test is based on 7% P&I and 360 months. I know I can use Solver but what if my NOI changes or if I want to run sensitivities. Is there a formula?