How long does it take for 1/2 cup of water to freeze?

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.

Could someone with number 1 and 2

An elevator travels 310 feet in 10 seconds. at that speed, how far can't his elevator travel in 12 seconds?