How to combine two column from two different table into one.

I have created a two different distinct column from two different table, now i want to show in my chart the combine sales value from both tble and want to combine those two distinct column into one..how do i do that.

For example in my chart i am showing the total sales value (Table A Sales+TableBSales) from both the table, now i want to show in legend the combine category name, but i am not able to do that

any idea how to do that?