How to rewrite DAX query?

I've created following DAX calculated column with help of variable. I've tried to do the same without variables, but for me using variable is much more simpler.  

Besides is it possible to rewrite following query without variables (I don't need actual query, just yes or no, and which functions should I use)?

CountByMonth = var current_date = 'questions'[Creation Date Dim]
var total = SUMX(FILTER('questions','questions'[Creation Date Dim]=current_date), 'questions'[Count])
return 'questions'[Count] / total

Are there any performance implications, if I'm using variables instead of direct query?