faire le cacul pour moi pour trouver la frequence de parents d, eleves entre 95 euros et 110 euros. je suis bloquée reponse

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.

The function show two sisters' savings account and the rate at which they plan to deposit money

I’m really confused and need your assist me with this question i’ve never been taught