Answer:
6.93 cm
Step-by-step explanation:
You have a right triangle (90°), so you do as follow:
If I understand correctly, you are looking for the hypotenuse so

That is equal to 
Is there a picture to go with this problem?
Answer:
10
Step-by-step explanation:
10/-5 = -2
-2+-2 = -4
Step one:
ALWAYS set equation equal to zero, which in this case has already been done for us.
Step two:
Figure out what formula you need to use in order to solve in this case I'd use the Quadratic formula.
a=1
b=9
c=2
Quadratic formula:

Then you would plug in the information.

The solve for what is underneath the square root ONLY.

Since you cannot solve this any further, your final two answers are...

First find the amount of tax by multiplying 21 × 8.5%.
.085 × 21 = 1.785 = 1.79 (rounded)
Now add the tax back into the price...
21 + 1.79 = $22.79