2/3 + 3/8. dude I literally just need this one question

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.

Find the number of liters in 12.8 gal of gasoline. round to the nearest hundredths

Through non-collinear points there is exactly one plane.