You can
put this solution on YOUR website!Grade for first eaxm =65%
grade for second exam = 85%
grade for third exam =77%
overall grade =20%
grade for final exam =x
overall grade = 40%
total grade =80%
(65% +85% 77%)20% +x*40% =80%
227% *20% +x*40%=80%
45.4% +40x% =80%
40x% =80%-45.4%
40x% = 34.6%
x% = 34.6%/40%
x%= 0.865
x=86.5%
grade score for final exam =86.5%