Having trouble with this math problem on related rates.
It is estimated that the annual advertising revenue received by a certain newspaper will be thousand dollars when its circulation is x thousand. The circulation of the paper is currently 14,000 and is increasing at a rate of 4,000 papers per year. At what rate will the annual advertising revenue be increasing with respect to time 2 years from now?
R(x)=0.5x^2+2x+155