The position of a ball as a function of time is given by x = (5.0 m/s)t

Question:

The position of a ball as a function of time is given by x = (5.0 m/s)t + (-10 m/s2)t2.
(a) What are the initial position, initial velocity, and acceleration of the ball?
(b) Plot x versus t for t = 0 to t = 2.0 s.
(c) Find the average velocity of the ball from t = 0 to t = 1.0 s.
(d) Find the average speed of the ball between t = 1.0 s and t = 2.0 s.