How to show a calculation output just one time (not in a column for every record)?

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Hi, 

EXAMPLE: We have a report that has a calculated column of "Total Time" (sum (......)), and another calculated column of "Total Quantity" (another sum (......)).  

We want to show the "TOTAL AVERAGE" that is Sum(TotalTime) / Sum(Total Quantity). This is the calculation of two separate columns (that's why I can't use the standard "average" option).

I have the expresion to calculate it, but I don't know how to show it just in one output (not a column, because it would show in every record.). Is there a way?

 

I tried to put in in a Variable & show it in a Text Field, but the Text Field is showing the expresion, not the calculation. I am attaching you an image.