The Fundamental Counting Principle states that if you have multiple choices and you want to find the total number of combinations of those choices, you can multiply the number of options for each choice together.
In this scenario, the choices are:
- Selecting a topic: There are 15 different topics to choose from.
- Choosing a presentation method: There are 3 different methods available (written report, oral presentation, or making a game).
To find the total number of different project combinations, we multiply the number of topic choices by the number of presentation method choices:
\[ \text{Total combinations} = (\text{Number of topics}) \times (\text{Number of presentation methods}) = 15 \times 3 \]
Calculating that gives:
\[ 15 \times 3 = 45 \]
Thus, the total number of different project combinations is 45.