You are enrolled in a wellness course at your college. you achieved grades of 70, 86, 81, and 83 on the first four exams. the fina exam counts the same as an exam given during the semester. a.) if x represents the grade on the final exam, write an expression that represents your course average (arithmetic mean). b.) if your average is greater than or equal to 80 and less than 90, you will earn a b in the course. using the expression from part a for your course average, write a compound inequality that must be satisfied to earn a b.