Combining numerical columns for average

I have a data set with scores attributed to each row. There are 5 different fields that contain these scores. I want to combine all of these columns into 1 column I can average so I can get an average of the entire data sets scores on which I can filter from other fields.

Is there a simple way to do this or another option that doesn't involve merging columns? When I tried to add column and merge the columns it didnt seem to work but maybe my syntax was off.