A motorcycle, which has an initial linear speed of 8.1 m/s, decelerates to a speed of 1.9 m/s in 6.7 s. Each wheel has a radius of 0.67 m and is rotating in a counterclockwise (positive) directions. What is
(a) the constant angular acceleration (in rad/s2) and
(b) the angular displacement (in rad) of each wheel?