Question 1185206
<br>
The first grade, 91, is +1 compared to the desired average.
The second grade, 86, is -4 compared to the desired average.
The third grade, 85, is -5 compared to the desired average.<br>
All together, the three grades are +1-4-5 = -8 compared to the desired average.<br>
That means the next score has to be +8 compared to the desired average.<br>
ANSWER: 90+8 = 98<br>