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4 Answers

There is a shortcut formula for the uniformly accelerated motion, relating the distance traveled, initial  and final velocities, and acceleration.
Here a is acceleration and vi and vf are initial and final velocities, respectively.
In your case vf=0 (truck stopped), vi=28 m/s, d=191 m.
191=(02-282)/(2*a) or 191=-392/a, from which a≈-2.05 m/s2. Now, when you know acceleration, time needed to stop can be computed from the formula:
a=(vf-vi)/t or t=(vf-vi)/a; Plugging in numbers gives t=-28/(-2.05)≈13.6 s.