To say return this day - 7 days in Spreadsheet

I am trying to list all days of lotteries in Eurojackpot history which is every sunday.

So last day when played 2.1.2015.

Pseudocode where edate is not the function of Libreoffice, since it only supports months

edate(date(2015,1,2); ; -7)

where syntax edates( [date]; [monhts]; [days]).

How can you minus seven days from timestamp in Spreadsheet?

simply with =DATE(2015;1;2)-7