Need to catch up on some algebra... don't know where to start...

I think this problem is algebra... it says I need to know it to move on to the next chapter... *but I'm in Geometry... I'm suppossed to not do algebra anymore!* *sigh*

**Evaluate each expression for the given value of n.**

3n - 2;n = 4

(n+1) + n;n = 6

There are several problems like these in different forms, but first could someone walk me through the steps of how to find the answer to these, and please, for the love of pizza, could someone tell me what the ";" does?? It must do something simple right? The ";" is what I don't know what to do with I guess... I've never seen problems like this... :o