You have the following function:

Derivate implictly the previous expression, as follow:

Where you have used that:

Then, the implicit derivative of the given expression is:

Next, solve for y' as follow:

U is right u gunna fail LOL
Its asking how much did they both spent, in total, in order to reach the same amount spent in part A
Multiply:
6•12=72
Then, you subtract 39 from 72:
72-39=33
33 containers would still need to be set up.
Answer:
68%
Step-by-step explanation:
17% × 4
68%