Answer:
The answert is "$0.007 / bottle".
Explanation:
Please find the complete question in the attachment file.
![\to R(x) =7.5x^(0.7)](https://img.qammunity.org/2022/formulas/mathematics/college/hw1b1lxumryda6noulb3kzflg8oavhzpmv.png)
The average income:
![\to A(x) = (R(x))/(x) =7.5 x^(-0.3)](https://img.qammunity.org/2022/formulas/mathematics/college/sc2xg5rakgsx9y5s6mldj9ugl09wt38hg5.png)
The change rate on the average revenue:
![\to A'(x) =7.5(-0.3)x^(-1.3)](https://img.qammunity.org/2022/formulas/mathematics/college/cw1ndf89p7ij5ndr426v9nk7j7pn1u08rr.png)
when 81 bottles were produced , then the rate of change in average revenue
The average income is decreasing at rate = $0.007 / bottle