Ezra decides to charge per dog instead of per hour. How does the solution set change? What are the limitations on x and y? Explain.

The limitations on y-values changed from nonnegative multiples of one-half to whole numbers, since Ezra cannot walk a fractional number of dogs.  The limitations on x-values did not change and must be nonnegative multiples of one-half, since Ezra cannot work negative hours and charges by the half-hour.