Question 206917
Let  P =  project  grade,,,and  E = Exam  grade
.
40% * P + 60% * E = 90
.
.40*86 + .6*E = 90
.
34.4 + .6*E = 90
.
.6E = 55.6
.
E = 92.67
.
Check,,,.4(86) + .6(92.67 = 90,,,,,ok
.