Answer:48
Step-by-step explanation:
I suppose you mean

Differentiate one term at a time.
Rewrite the first term as

Then the product rule says

Then with the power and chain rules,

Simplify this a bit by factoring out
:

For the second term, recall that

Then by the chain rule,

So we have

and we can simplify this by factoring out
to end up with

20x + 25 = 165
x represents the number of bags. You can solve the equation to make sure the answer is 7.
20x + 25 = 165
Subtract 25 from both sides.
20x = 140
Divide 20 off of both sides.
x = 7