The function is stating that the number of players (p) is equal to the number of teams (t) multiplied by 8 (8t).
So to find your values, you plug the t value into your equation to find the number of players you need.
For example, 2 teams, you'd write the function as p = 8t and substitute the t for 2. So p = (8)(2), which gives you p=16.
Now try for team 3 and post your answer if you're unsure and I'll check it