To find the length of the punt, we equate the expression to zero i.e. f(x) = 0 ,Given, f(x) is the height (in feet) and x is the horizontal distance (in feet) from the point at which the ball is punted. or (-16/1225)x^2 + (7/5)x + 2.5 = 0. On solving for x we get, x = 108 ft.