Find out what score you need on your final exam to reach the grade you want, based on your current grade and the final's weight.
Your current grade counts for everything except the final, and the final counts for its weight. The tool solves for the final score that makes the weighted total equal your target: (target − current × (1 − weight)) ÷ weight.
Then your target is out of reach with the final alone, even with a perfect paper. Either set a lower target, or double-check the final's weight and your current grade.
It means you have already done enough. Even scoring zero on the final would leave you at or above your target, so the requirement is effectively nothing.