Answer:
the average velocity of the ball is 5 m/s.
Explanation:
Given;
initial position of the ball, x₁ = 12 m East
final position of the ball, x₂ = 8 m West
initial time of motion, t₁ = 10.0 s
final time of motion, t₂ = 6.0 s
The average velocity is calculated as follows;

let the Eastward direction be positive
Let the westward direction be negative

Therefore, the average velocity of the ball is 5 m/s.