Relative Velocity of Stone?

1. The problem statement, all variables and given/known data

A stone is dropped from a balloon at an altitude of 300 metres. How much time is required for the stone to reach Earth if:

(1) Balloon is ascending with a velocity of 5 m/s,

(2) Balloon is descending with a velocity of 5 m/s

(3) Balloon is stationary

Disregard air resistance.



2. Relevant equations

[itex] x=x_0+v_0t-1/2gt^2 [/itex]

[itex] v=v_0-gt [/itex]



3. The attempt at a solution

I have no problem with question 3 but I fail to understand how the ascend or descend of balloon affect the stone. I assumed that it affected the initial velocity of the stone but I can't seem to find the formula for time.