If an arrow is shot upward on the moon with a velocity of 58 m/s, its height

Question:

If an arrow is shot upward on the moon with a velocity of 58 m/s, its height in meters after seconds is given by h = 58t - 0.83t2.
(a) Find the average velocity over the given time intervals:
(i) [1, 2] (ii) [1, 1.5] (iii) [1, 1.1]
(iv) [1, 1.01] (v) [1, 1.001]
(b) Find the instantaneous velocity after one second.