Vertical Motion w/ constant acceleration

[cdlegendary]

Homework Statement

A ball is thrown straight up from the edge of the roof of a building. A second ball is dropped from the roof a time of 1.14 s later. You may ignore air resistance.

A.) If the height of the building is 20.6 m, what must the initial speed be of the first ball if both are to hit the ground at the same time?

Homework Equations

vf^2 = v0^2 + 2ax
vf = v0 + at
x = x0 + v0t + 1/2at^2

The Attempt at a Solution

I'm really not sure where to start. If someone could help me out I would greatly appreciate it.

 

[ideasrule]

Focus on the last of your three equations. "t" has to be the same for both objects: the one that's dropped, and the one that's thrown up.

 

[cdlegendary]

Focus on the last of your three equations. "t" has to be the same for both objects: the one that's dropped, and the one that's thrown up.

Hmm but wouldn't there be two unknowns for that equation? I tried setting the equation equal to itsel but it turned out kind of badly, haha...