Not possible with just XL...if you want to use VB, you could try this.
Right click on sheet tab, view code, paste the following in:

'=============
Private Sub Worksheet_Change(ByVal Target As Range)
'If not changing A1 or B1, or if you change a group of cells
'then do nothing
If Intersect(Target, Range("A1:B1")) Is Nothing Or _
Target.Count 1 Then Exit Sub

Application.EnableEvents = False
If Target.Address = Range("A1").Address Then
'Formula that controls B1
Range("B1").Value = 0.2 - Range("A1").Value
Else
'Formula that controls A1
Range("A1").Value = 0.2 - Range("B1").Value
End If
Application.EnableEvents = True
End Sub
'=============

Back in XL, you can then change A1/B1, and the other cell will change
accordingly.

--
Best Regards,

Luke M
"Chris" wrote in message
...
ok, so it's not possible...thanks anyway
Chris

"Eduardo" wrote:

Hi,
if you enter the % in both cells you will overwrite the formulas you need
to
have the formula in one cell,


"Chris" wrote:

This would work in one direction. is it also possible for both
directions so
i could change percentages in A1 or in B1?

Thanks,
Chris

"Jacob Skaria" wrote:

In cell A1 enter 20% and in cell B1 enter formula

=0.2-A1

--
Jacob


"Chris" wrote:

I'm working on a Excel sheet where I have to connect two formulas
as follows:

A1 and B1 have together a value of 20%. if A1 is 12%, B1 should
automatically shows 8% and vice versa. I tried it with A1: =0.2-B1;
B1:
=0.2-A1 but its not working properly. Could someone please help me?

Thanks in advance!