Question 1010562
You have 5 test trying to get an average of 80, so multiply the 5 test you are taking times the average to see the sum of all your grades, 80*5= 400, now subtract the ones you know, 400-89-84-65-92-70, and you get 89, you can check this by adding up all your known grades plus 89 and dividing it by the grades getting an average of 80, 89+84+65+92+70+89= 400/5= 80.