Answer:

Step-by-step explanation:
We want to simplify:

We rewrite as positive index to get:

This simplifies to

This will finally give us:

We cannot simplify further.
Hence the simplest form is 
Answer:
85
Step-by-step explanation:
add 4 values, excluding 72 (lowest grade)
total = 339
average = 330/4 = 84.75
84.75 rounding to nearest integer is 85
Answer:
X=90
Step-by-step explanation:
x=90 because it is a right angle.
hope that helps!