Answer:
94%
Step-by-step explanation:
The whole thing is about averages. Currently the average an 87%, because 85+91+86 = 262. 262/3 = roughly 87%.
Now if she got another score, that would mean it would now be divided by 4 instead of 3. So the equation is:
(262+x)/4 = 89
*4 *4
____________
262 + x = 356
-262 -262
____________
x = 94
