The formula is
The initial velocity being 27m/s, the final velocity will be -27m/s when the ball comes down at the same height as it has been thrown. The acceleration is negative since it is in the opposite direction to your initial velocity. So, set u to 27, a to -9.81 and v to -27. Solve for t to get the time the ball was in the air. (ans: 5.5 s)
Use

to find the max height.
The initial velocity is 27 m/s, the final velocity is 0 m/s (since it is at the maximum height), and the acceleration is -9.81 m/s^2 (since it is again in the opposite direction to your initial velocity). Solve for s, the displacement. (ans: 37.2m)