Ball thrown vertically up from building and falls to ground

A rock is thrown vertically upwards with a velocity of 29.4 m/s from the top of a building 78.4 m high. After how long will the rock reach the ground below? (Take g = 10 m/s2)

Many are familiar with calculation when ball is released from rest. This question involves ball being thrown upwards, and then it falls to the ground. To solve this question, just treat the motion as 2 separate parts.

1) Ball going up to max height,

2) Ball going down (similar to ball released from rest from highest point)