Can someone help me with this math!

Jim is painting the inside of a circular helicopter pad. how many cans of paint would he need if the pad is 50 feet across and each can of paint covers about 200 ft2.

If myesha works overtime, she gets paid "time and a half" for every hour she works. in other words, for every hour over 40 hours myesha works each week, she gets her hourly pay plus half her hourly pay. what is myesha's pay per hour when she works overtime?

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.