The answer is 51 (not sure of the measurement unit). Assuming you mean the football hits the ground when it's kicked and lands somewhere downfield, y would be 0 (y means height from the ground, and if something is on the ground, it has no height. Hence, the 0). Set the equation equal to 0 and factor to solve for x. 0 = -.03x(x-51). 0 = -.03x and x = 0, or 0 = x-51 and x = 51