You are not very good at expressing your question either ;-)

The formula for 4-2 is "4-2"

Looking at your graphic, it appears that you a have a 3x4 table (3 columns
and 4 rows).  These are laid out
a1  b1  c1
a2  b2  c2
...

If you want to display the difference of the value in b2 minus the value in
c2,  then put the formula in a2 using the following syntax:

{=(b2-c2)}

The field pairs {  } are entered with CTRL+F9