If your computer still doesn't know how to open it, right-click -> "Open With" -> Choose 7-Zip or WinRAR.
Have you managed to get it opened? Let me know in the comments if you encounter any errors like "file corrupted" or "unknown format"! Contextual Information from Search Results Download Argos18 rar
Select > Extract Here (or "Extract to..." to choose a folder). If your computer still doesn't know how to