7 because 8+7 is equaled to 15
I think that the fencing is needed
Given:
Marginal revenue (in dollars per unit) for a month is

To find:
The total revenue from the production and sale of 30 units.
Solution:
We know that, total revenue is integration of marginal revenue with respect to quantity.




Now, substitute x=30 in the equation of Total Revenue (TR).




Therefore, the total revenue from the production and sale of 30 units is $11,775.
PEMDAS
Parentheses, Exponents, Multiplication, Division, Addition, Subtraction.
The answers are A, D, and E.