power bi relationship

Hi all.
I'm totally a beginner ... and I need a lot of help from you.
I have an excel file. With the help of Power BI I would like to get the following thing:
The "startstock" worksheet compares it to the "endstock" worksheet and see what quantity is consumed only for the items that are on both the first worksheet and the second worksheet (I may have articles Which are not found in both worksheets).

The file is here https://www.dropbox.com/s/p4hswvs1ltupszd/ian2016.xls?dl=0

thx in advance.