#### Answer

Your score on the next test must be between 85 and 100, inclusive.

#### Work Step by Step

Write a compound inequality
$85 \leq\frac{83+87+x}{3} \leq 90$
$255 \leq 170+x\leq 270$
Subtract 170 from each part.
$85 \leq x \leq 100$
Your score on the next test must be between 85 and 100, inclusive.