It shows that the extra 6 in mathematics is given to Chinese and English, while Chinese is 90-86=4 points less than English.
Then 6 points are given to the Chinese first, and there are 2 points left. Divide these two points equally between Chinese and English, and get the average score.
So the average score is 86+4+1= 90+1= 91,and the math score is 9 1+6=97.
Hope to adopt!