your tutor left you with Energy Equation:

hope you notice that in this problem:

1) the mass is constant

{ there is no need to change this to grams (it will only complicate if you do so), so leave it in kg...see #4 }

2) you can also assume that gravity (g) is constant

3) Point A is 1500m higher than point B.

For your convenience assume B is ground level. So, would be 0 and would be 1500 m as you guessed

4)) The resistance to motion is constant at 300 N

since,

let us keep everything consistent to that unit.

i.e. keep mass in kg, distance in m, and time in seconds.

keeping that in mind, you should change velocity to

edit: i think you should visit http://www.physicshelpforum.com/physics-help/ for further help. Afterall, it is a physics problem.