The total monthly revenue R(X), in dollars, generated from sales of Calculus videos is related to the amount X spent on advertising by R(x)= 4x3 + 48x2 + 30x + 40 where x is in hundreds of dollars. Compute the rate of change of revenue with respect to the amount of money spent on advertising. R'(x) = 15 monthly revenue increasing faster when the amount of money spent on advertising is 320 dollars or 420 dollars? 0 320 dollars 0 420 dollars