Question 990785
.
The sum of 5 grades to average 90 is (5)(90)=450
Let x=4th score and y=5th score
450-70-85-94-x-y=0
201-x=y
.
Sam must get a score of (201-his fourth score) 
on his fifth test to average 90. 
(He must average more than 100% on tests 4 and 5).
.