A teacher weights student marks in her final calculation as follows: Knowledge and Understanding,20%;Application,15%; Thinking,20%; Communication,15%; and the Final Exam, 30%. A student's marks in these categories are 80, 78, 82, and 85, respectively. The final exam, has not, as yet, been written.

a) Calculate the student's term make before the final exam.

b)What mark must the student achieve on the final exam to earn a final grade of 85?