What is 13/20 simplify show steps and answers

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.

Anyone? 15m is what percent of 60m; 3m; 30m; 1.5 km?

Convert the mixed numbers into improper fractions. convert the improper fraction to mixed numbers.