custom average row in matrix

[nick9one1]

I have two SQL tables, one has scores per category, per month. The other has a weighted average total per month. 

In the image below I have them in two matix tables, the top table shows a normal average per month (which is incorrect), and the second lower table shows the correct weighted average. 

Is there a way to have the second matrix table row inserted as the final row of the top matrix?

[danextian]

Hi @nick9one1 

My question is how is the correct average being calculated? What formula does the second table have?

[nick9one1]

it isnt calculated in powerbi