Given
initial position = Xi= 19.9m
Final position Xf = 5.4m
Average velocity= Va = -0.418m/s
it shows displacement is reverse.
To find t=?
As Va = (Xf- Xi) / t
t = (Xf-Xi) / ( Va)
t = ( 5.4-19.9) / (-0.418)
t = (-14.5 ) / (-0.418) (-ve sign cancel out at numerator and denominator)
t =34.69 s