How do i do this???/

Start at the big tree, and take the instructions one at a time: 1). Walk 15 west. 2). From there, turn around and walk 2 east. 3). From there, walk 7 more east. Where are you from the big tree now ? Aren't you 6 west of it ? I mean, let's see some common sense here !

If you take the Western direction as the positive direction and the Eastern direction as negative one, then,

Distance traveled to the West = +15 m

Distance traveled to the east = (-2 m) + (-7 m ) = -9 m 

Total Displacement = 15 m + (-9) m 

Total displacement = 6 m

Since the total displacement is positive, the displacement will be in the Western direction.

So, option  (D) is correct.

The car would move to the right with 150 n of force. the 150 n of force from friction and air resistance slows the car from moving to the right with 300 n of force.