Combine Profit Center & Profit Center Description into single List Box

[#1]

If I have two fields "Profit Center & Profit Center Description" how do I have them combined to appear in a list box.

Example:

Profit Center:            Profit Center Description:

1005                        Tools

1006                        Electrical

How would I have them appear in a list box as:

1005 - Tools

[Anonymous · Accepted solution]

It will be:
="Profit Center" & ' - ' & "Profit Center Description"
or maybe, depending on where you use it:
=aggr("Profit Center" & ' - ' & "Profit Center Description"),"Profit Center")