The question I am working on is:
A stone is thrown vertically upward with a speed of 12.0 m/s from the edge of a cliff 75.0 m h. (a) How much later does it reach the bottom of the cliff? (b) What is its speed just before hitting? (c) What total distance did it travel?

I am lost I thought I was on the right track but then my friend showed me her work and now I'm even more lost.

You can answer all of these by letting the 'thrown from' position be the origin(0,0).

To find how long to get to the bottom of the cliff, use

y=v_{0}t-4.9t^{2}, set to -75 and solve for t. Of course, v_{0}=12

Also, you can use v=v_{0}-9.8t to find velocities at various points.