When the car comes to a stop, the final velocity must be 0 m/s.
Since the car js decelerating in a forward direction, acceleration must be negative.
final v = initial v + a•t
0 = 20 + (-6)t
t = 3.33s
I’m assuming you’re supposed to calculate the resultant force?
425N (right) -300N (left)
=125 N to the right
If there is no friction, the roller coaster would keep moving forever but a constant velocity. The only way it would accelerate is if there was a force continually pushing on it.
