Answer:
b. 
Step-by-step explanation:
Here we are given
and are asked to simplify it. We are going to apply the law of exponents which says that

Hence applying this rule in our problem we get, where a=y and n=3

Hence our C) Option is correct
C since 25ab and 5ba both have the terms "a" and "b"
Photo math helps it worked for me so might help you :)
I converted everything into decimals and went from there.
The number of gallons of water in the tank at t=10 is
... W(10) = 160,000 -10(8000 -10) = 80100
The number of gallons of water in the tank at t=10.5 is
... W(10.5) = 160,000 -10.5(8000 -10.5) = 76110.25
The rate of change over the interval is
... (W(10.5) - W(10))/(10.5 - 10) = (76110.25 - 80100)/(0.5) = -7979.5
The average rate of change in the number of gallons of water in the tank over the interval is -7979.5 gal/min.
The sign is negative, so the amount of water is decreasing.