calculate change in amount based on date

[NewbieFour4]

I get a weekly report with total goods sold up to a certain date. I want to be able to quickly calculate the difference between the goods sold between certain date (ex: increase since last week for Gen 1 is 25). Quick measures only do month over month, not week by week changes. See an example below. What calculation should I use? 

Date	name	total
19-Mar	Gen 1	25
19-Mar	Gen 2	50
26-Mar	Gen 1	50
26-Mar	Gen 2	100

[amitchandak]

You have to use Rank to do this week vs last week. This file has that

https://www.dropbox.com/s/d9898a48e76wmvl/sales_analytics_weekWise.pbix?dl=0

Look for 1st and 2nd Tab, Ignore WTD unless u need that