Dax to Calculate % change Week -1, week-2, week n

[SAMUEL_KIARIE]

Dimension	Week -0  (% change)	week -1 (%change)	Week -n (% change)
A	x	d	u
B	y	e	v

I want to be able to calculate the % change of the previous weeks when I select a week filter. i.e (Week - 0)% change = divide( a-b/b, blank())

a= calculate( sum(sales),filter(sales,global=1)
b= sumx( stock, supplier cost)
% change = divide( a,b, blank())
@help

[amitchandak]

@SAMUEL_KIARIE , check my WOW approach using rank can help

Have these new columns in Date Table, Week Rank is Important in Date/Week Table

Week Rank = RANKX('Date','Date'[Week Start date],,ASC,Dense)
OR
Week Rank = RANKX('Date','Date'[Year Week],,ASC,Dense) //YYYYWW format

These measures can help
This Week = CALCULATE(sum('Table'[Qty]), FILTER(ALL('Date'),'Date'[Week Rank]=max('Date'[Week Rank])))
Last Week = CALCULATE(sum('Table'[Qty]), FILTER(ALL('Date'),'Date'[Week Rank]=max('Date'[Week Rank])-1))
Last year Week= CALCULATE(sum('Table'[Qty]), FILTER(ALL('Date'),'Date'[Week Rank]=(max('Date'[Week Rank]) -52)))

Power BI — Week on Week and WTD
https://medium.com/@amitchandak.1978/power-bi-wtd-questions-time-intelligence-4-5-98c30fab69d3
https://community.powerbi.com/t5/Community-Blog/Week-Is-Not-So-Weak-WTD-Last-WTD-and-This-Week-vs-La...
https://www.youtube.com/watch?v=pnAesWxYgJ8

Time Intelligence, Part of learn Power BI https://youtu.be/cN8AO3_vmlY?t=27510
Time Intelligence, DATESMTD, DATESQTD, DATESYTD, Week On Week, Week Till Date, Custom Period on Period,
Custom Period till date: https://youtu.be/aU2aKbnHuWs&t=145s