Assuming the deceleration due to gravity is unaided by air resistance, gravity causes the ball to lose vertical speed at the rate of 32 ft/s every second. The initial vertical speed of 120 ft/s will decline to zero when t satisfies ...
... 120 ft/s - (32 ft/s²)t = 0
... (120 ft/s)/(32 ft/s²) = t = 3.75 s
The ball will not go any higher after its vertical speed is zero.
The LCM of 128 and 256 is 256. Steps to find LCM. Find the prime factorization of 128 128 = 2 × 2 × 2 × 2 × 2 × 2 × 2; Find the prime factorization of 256.