A company selling widgets has found that the number of items sold, x, depends upon the price, p at which they're sold, according the equation $\displaystyle {x}=\frac{{40000}}{\sqrt{{{4}{p}+{1}}}}$

Due to inflation and increasing health benefit costs, the company has been increasing the price by $3 per month. Find the rate at which revenue is changing when the company is selling widgets at $170 each.

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