Chapter 7.1, Problem 68E

Revenue, cost, and profit functions. A company manufactures 10- and 3-speed bicycles. The weekly demand and cost equations are

     $\begin{array}{l}p=230-9x+y\\ q=130+x-4y\\ C\left(x,y\right)=200+80x+30y\end{array}$

where $p is the price of a 10-speed bicycle, $q is the price of a 3-speed bicycle, x is the weekly demand for 10-speed bicycles, y is the weekly demand for 3-speed bicycles, and C(x, y) is the cost function. Find the weekly revenue function R(x, y) and the weekly profit function P(x, y). Evaluate R(10, 15) and P(10, 15).