I need to create a formula?

Question

I need a formula wich will create the sum red when it equals a minus.

Answer 1

This formula will put a minus sign in a second column's entry when the first column's entry is a minus or the positive value if positive.
A1=first entry
A2=second entry
Put into A2:
=IF(A1>0,A1,"-")

Answer 2

In Excel, you can format the cells to do it for you.

Select the cells and go to Format: Cells...

In the box on the lower right, there is an area describing how to handle negative numbers.


There are alternate approaches, but not knowing what you are trying to do, or in what system, I don't want to go on at this point.