Please help with this question I need help on the first one if you help with both it would be greatly appreciated

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.

If i have a 24 in loaf of bread and i cut it into two pieces one 9 in how long was the other

Is there an x intercept in the equation 60*1.15^x