using bfr tax, after tax and inflation for IPS return

can someone please clarify which is the correct way to use this info cuz I have seen answers with different ways of doing it in both schweser and cfa previous answers…both would give a significantly different answer bfr tax = (after tax+ inflation)/(1-tax) OR bfr tax = (after tax)/(1-tax) + inflation appreciate the help!

I am going with (1+R)(1+I)-1/(1-T),736453,736498#msg-736498