How can we tell that 4:1 and 12:3 are equivalent ratios?

The change in water level of a lake is modeled by a polynomial function, w(x). described how to find the x-intercepts of w(x) and how to construct a rough graph of w(x) so that the parks department can predict when there will be no chage in the water level. you may create a sample polynomial of degree 3 or higher to use in your explanations.