To open a 7Z file right-click over the file and select 7-Zip from the menu and then Open archive.
Select the first Open archive option, not the second one.
Double-click on any file or folder to open it. If the 7Z file is password protected, you'll be prompted to enter the password before you can open the file.
If you want to extract the files to a specific location, click the Extract button. You'll be asked for a location to extract the files to and, if there is a password on the file, you'll be prompted to enter the password.
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