Answer:
The hourly fee for rototiller is $3 per hour.
Step-by-step explanation:
We are given the following in the equation:
The rental company charged an initial fee of $43 with an additional fee per hour.
Let h represents the hourly fee.
The family paid $64 after renting the rototiller for 7 hours.
Thus, we can write the equation:

Solving the equation, we get,

Thus, the hourly fee is $3 per hour.
Equation:

where C(x) is the cost function and x is the number of hours rototiller is rented.
The hourly fee for rototiller is $3 per hour.
Required expression is x/9 - 7
<span>A(t) = −(t − 8)2 + 535
You would like to find the maximum of this function:</span> −(t − 8)^2<span>This part is always negative or zero as a number squared cannot be negative and you multiply by -1: Thus the maximum of this part MAX:</span>−(t − 8)^2=0
<span>The max will be when t=8 and its value is 535
</span>
The answer is 1.12% decrease
Explanation in image