Profit is the difference between revenue and cost. the revenue, in dollars, of a company that makes skateboards can be modeled by the polynomial 2x^3 + 30x -130. the cost, in dollars of producing the skateboards can be modeled by 2x^3-3x-520. the variable x represents the number of skateboards sold. what expression represents the profit?

a: 27x-650
b: 27x+390
c: 33x-650
d: 33x+390