A ball is thrown horizontally from top of a sky-rise building 144 ft high with a velocity of 20 ft/sec. Neglecting air resistance, find d?

Vertical component of the motion of the ball:
displacement, s = 144 ft
initial velocity, u = 0 ft/s
acceleration, a = g = 32 ft/s²

s = ut + (1/2)at²
144 = 0 + (1/2)(32)t²
16t² = 144
t² = 9
t = 3 s

Horizontal distance travels, d
= 20 × 3 ft
= 60 ft

falling time t = √2h/g = √144*2/32 = 12/4 = 3.00 sec
horizontal distance x = Vo*t = 20.00*3.00 = 60.00 feet

Find d? What is d supposed to represent in that problem?