I believe the answer would be b^4.
Explanation:
Use Quotient Rule: x^a/x^b=x^a-b
b^10-6
Then Simplify 10-6 to 4
b^4
Answer:

-8 to the power of 0 = 1
(Anything to the power of 0 = 1)
and 6 to the power of -1 = 1/6
( Any number to the power of a negative number will become a fraction)
Example.

So is will be 1/6 over 1
Which gives you your final answer.
First, change 2/5 into a decimal by dividing 2 by 5. Decimal= .4. Now move the decimal 2 places to the right to find percentage. Answer is 40%
Perimeter is distance all around the side of the figure, so you would do:
8 + 7 + 19 + 3 + y + x
Plug in y and x that you solved before: 8 + 7 + 19 + 3 + 11 + 4
Add them!: 52
The perimeter is 52 meters.
:)
Just add 2.5 + 13.5 (16) and multiply it my ten (160)