For the following exercises, construct a system of nonlinear equations to describe the given behavior, then solve for the requested solutions.

A cell phone company has the following cost and revenue functions: C(x) = 8x² − 600x + 21,500 and R(x) = −3x² + 480x. What is the range of cell phones they should produce each day so there is profit? round to the nearest number that generates profit.