An 18-lb shell moving with a velocity v0 = (60 ft/s)i??(45 ft/s) j ?? (1800 ft/s)k explodes at point D into three fragments A, B, and C weighing, respectively, 8 lb, 6 lb, and 4 lb. Knowing that the fragments hit the vertical wall at the points indicated, determine the speed of each fragment immediately after the explosion.