Formal:
* The lawyer presented pertinent evidence to support her client's case.
* The article discussed pertinent issues regarding the current political climate.
* The professor only asked questions pertinent to the topic of the lecture.
Informal:
* I tried to keep my comments pertinent to the discussion at hand.
* She gave me some pertinent advice about my job search.
* The website has a lot of pertinent information about planning your trip.
Note: "Pertinent" means relevant or applicable to a particular matter. It's a slightly more formal word than "relevant," so consider the context of your sentence when choosing which word to use.