Problem combining measures on current month and previous month

Hi all,

I'm trying to combine two measures on a graph, one wich calculate, at the latest alimentation date, result of current month, another wich calculate, the 2nd of current month, result of previous month ? 

For example, we are 08/05 and my performance of this month (august) is so far of 25%. Previous month performance (july) was calculated 08/02 and is of 80%.

Alimentation date is on my x axis, I would like to display 80% in july and 25% in august.

Any idea how to achieve this ? I tried using dateadd function but it didn't do anything.

Thank you in advance for your help.

Regards,

Alice