Can I (and how to) install sims 3 expansion packs when my base game is on origin?

I've been looking all day but I can't find a topic that explains how to do it.

I have downloaded all the expansionpacks that I want to install, and I know how to install them, but how do I get them to work? The game won't even start up. 

Where do I need to put the cracks? Or what else do I need to do?

Hello, and welcome to the forum, 
you can add pirated addons to The Sims 3 from Origin. Download WinRAR, if you haven't alerady. Install Manual Patch to install latest version 1.67. 

Right click on addon you want to install and select Extract Here. Now run the setup of addon and follow installer. When installer asks you for a serial code open #Installation Guide and use it to enter serial code. Do not follow steps inside #Installation Guide other than serial code, as they are outdated. Install all addons you want.

Now, download Ultimate Fix. Right click on download file and select Extract Here and copy files from folder #Crack to install directory of The Sims 3, it's usually C:\Program Files (x86)\Electronic Arts\The Sims 3\Game\Bin. Your game now should run.

May I ask what version are you on?

When I try to install the manual patch, it says that i'm already on that version.

Does it matter where I save the expansions?

And since I downloaded and installed my base game on origin, I don't have the C:\Program Files (x86(\Electronic Arts\The Sims 3\Game\Bin folder. I do have the C:\Program Files (x86)\Origin Games\The Sims 3\Game\Bin, but if i put thecrack in there, won't it ruin the game?

Open The Sims 3 launcher and in lower right corner you'll see that it says version. Write exactly what version it says. 

No, it doesn't matter where you save expansions.

I will ruin game in some way. Now, your game is legal, but when you put crack, and install expansions, it'll become pirated. Either, play like that or download The Sims 3 Base Game from here and have fully pirated game that won't interfiere with your Origin one.

The version is 1.69.43.024017

Sadly, you can't install expansion, because new crack isn't, and probably won't be created. So, download Base Game from here and install it. Then install addons you want.

Thank you!

Yes, you can mix legal and pirated games but you'll need downloads in .iso or .daa format and mount the downloads in a program called PowerIso.
However, I presume that with the G4TW downloads they can be mixed as well, provided you have your highest installed game, f.e. Into the Future as a legal or a pirated .iso game.
In that case do not use the cracks in the downloads.