The first thing you’ll notice after installing Linux Mint is that Google is missing from the search engine list in Firefox. The second thing you’ll notice is how it’s not obvious how to put it back, and searching the web for an answer is a frustratingly fruitless experience.
So click on this link
http://mycroftproject.com/google-search-plugins.html
And scroll down the list, clicking on the search engines you’d want to add to your Firefox search engine list in Linux Mint. I chose SSL Google UK (18 up from the bottom in the list of 209 different engines).
Once you’ve clicked on it, you’ll notice that it will be back in the list. You can then Manage Your Search Engines in Firefox and change the order to move Google to the top.