How do you get rid of a fraction?

Suppose that the price p (in dollars) and the weekly sales x (in thousands of units) of a certain commodity satisfy the demand equation 4p cubedplusx squaredequals38 comma 400. determine the rate at which sales are changing at a time when xequals80, pequals20, and the price is falling at the rate of $.20 per week.

Twelve less than a number is at most 20

If a line is defined by the equation y = 5x + 2, what is the slope?