Answer:
80%
Explanation:
So first you want to add all the scores together and you will get 430 and if you divide that by 5 you will get 86%.
You want to find the right number to add to the scores to get an average of 85%. You want to find the right numbers and divide the sum of the numbers by how many numbers there are.
In this case the number you need to add is 80. When you add 80 to 430, you get 510. Divide 510 by 6 and you get 85%.
Answer is 80