A rock is thrown horizontally off a 38-m high building with an initial velocity of 28.0 m/s directed away from the building. How far from the base of...

A rock is thrown horizontally off a 38-m high building with an initial velocity of 28.0 m/s directed away from the building. How far from the base of the building does the rock land?

The answer is 78.0m

Please provide step-by-step solution to how this is the answer.