Roolling previous weeks

[ADRICHECKIN]

Hi team,

Best way to calculate "sales" for current Week, Last week, -2 weeks...and so on? Considering weeks starts on Monday. I have read many about, but withouth a clear idea of how to do. 

A table as example.

DATE	DAY	WEEKNUM	SALES
26/12/2020	sá	52	140 €
27/12/2020	do	52	150 €
28/12/2020	lu	53	160 €
29/12/2020	ma	53	170 €
30/12/2020	mi	53	180 €
31/12/2020	ju	53	190 €
01/01/2021	vi	1	200 €
02/01/2021	sá	1	210 €
03/01/2021	do	1	220 €
04/01/2021	lu	2	230 €
05/01/2021	ma	2	240 €
06/01/2021	mi	2	250 €
07/01/2021	ju	2	260 €
08/01/2021	vi	2	270 €
09/01/2021	sá	2	280 €
10/01/2021	do	2	290 €
11/01/2021	lu	3	300 €
12/01/2021	ma	3	310 €
	sales current week	3	610 €
	sales last week	2	1.820 €
	sales -2 week	1	630 €
	sales-3 week	53	700 €

I really apreciate for help!

[amitchandak · Accepted solution]

@ADRICHECKIN , Using week rank in Date table, You can try.

Refer my Power BI — Week on Week and WTD  blog and video
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

[ADRICHECKIN]

Thank you very much. Easy, simple and work perfectly!