questions about flight computer

hello,
i want to reproduce a flight computer,calculator,
but i have a pb with three equation, how to find the relation between:

Actual Landing Distance (ALD)
with
Normal Landing Speed (NLS),Required Landing Distance (RLD) and Tail Wind Component (TWC)


to find
Actual Runway Needed (ARW)
with
Regulatory Takeoff weight (RTW),Additional Load (ALD) and Takeoff Distance (TOD)


and finally, to find
Actual Landing Distance (ALD)
with
Normal Landing Speed (NLS),Required Landing Distance (RLD) and Tail Wind Component (TWC)

thx u very much

This is all depended on TYPE aircraft and it's weight and balance.

Matt Olieman

ok but why in the flight calculator,
when i put
NLS = 200
RLD = 1000
TWC = 20

there is a result > ALD= 1210
how to find this ALD?