The size of the acceleration is
(change in speed) / (time for the change) .
Change in speed = (60 m/s - 2 m/s) = 58 m/s
Time for the change = 4.0 s
Size of the acceleration = (58 m/s) / (4.0 s) = 14.5 m/s² .
We don't know the direction of the velocities, so we can't say anything
about the direction of the acceleration.