The total monthly revenue R(x), in dollars, generated from sales of Math t-shirts is related to the amount x spent on advertising by R(x)=-6x3 + 108x2+ 30x + 80 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 ) = Is monthly revenue increasing faster when the amount of money spent on advertising is 540 dollars or 620 dollars? O 540 dollars 620 dollars