Plz need help its due today after class

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.

Kathy spent 5/8 of her money on books and another 1/6 of her money on stationeries.what fraction of kathy’s money was left?

Pls brainliest will be awarded if answer is correct