Here is the equation:
You need to find f(3). To do that, substitute all the x's with 3:
The first thing you need to do is multiply 4 by 3. Multiply:
Here is your new equation:
To get your answer, you need to add 12 and 1. Add:
That means:
<em>If you have any questions, feel free to ask in the comments! :)</em>