The other answers are theoretically correct, but grades are usually weighted. If this debate was an important assignment your grade could go up to 75. If it wasn't important to the teacher, it could stay the same. The good news is that it won't go down. The traditional way of calculating is to add up the grades and divide by the number of assignments, but as I said, the assignments could be weighted. So, the debate could count as 1 or 2 assignments.
