I am not exactly sure how to solve this. Any help would be appreciated.

The path of an object after it has been thrown off of a building can be represented by the quadratic equation y = - x + 16x +80 where y is the object's vertical distance from the ground in feet and x is the horizontal distance in feet from where it was thrown. How far will the object travel in the horizontal direction before it hits the ground? O a.) 2 feet ( b.) 20 feet O c.) 80 feet O d.) 4 feet