answer:(score * weight) + (score * weight) = final .75 * .65 + X * .35 = .80 We solve for X to get X = .892857. If you need more steps, tell me. So, an 89.28% is the target for the exam grade. To be completely sure of a final grade of 80%, you might need a 90% on the exam. If your final grade is rounded to the nearest percent, you might be able to take an 88%, but no less.