7 Units.
8(1)+9= 17
8(2)+9=25
8(3)+9=33
33-25=7. 25-17=7
Let the score on her seventh test be "x".
SO,

∴ He must get 104% on his seventh test to get an average score of 90%
It would be 224 , the base is 64 and every triangle is 80 but if you follow the rule for area to a triangle you get 40
So 64+40+40+40+40= 224