Forget the formulas
If you operate any aircraft you are responsible to know your performance!
That's why there is a QRH next to the Pilots and a FCTM. All is covered.
So whether you land with a TWC, one or both rev. inop, anti-skid inop, etc., its your job as CM1/CM2, PIC, PICUS, or FO to know the basics...... will the ac stop or not.
So no excuse to land anywhere (and unless a surprise mechanical failure of spoilers, brakes, etc. upon touchdown... or an environmental factor (damp, wet, contaminated)- Downburts, etc.) and go off the end or side of the runway (only excuse a miro-burst from the side or gear collapse).
You should always be able to stay on a 45m wide runway and within the LDA!
If not, the choice is obvious.
If you cannot manage this, then WTF are you doing in a cockpit.
So a tip. Next time you land. Take the QRH or whatever, look at your performance and ask your self - where will I stop if I land at the 3,000 ft mark (end of the Touchdown Zone) with above mentioned failures.
I bet you it may be the first time?