Calculating the Height of a Cliff Using the Speed of Sound

[afa]

Homework Statement

A rock is dropped from a sea cliff, and the sound of it striking the ocean is heard 3.7s later. If the speed of sound is 340m.s how high is cliff?

Homework Equations

Ttotal=trock+tsound distance=Vsound*tsound ts=340m/s-trock x=x+vt+.5at^2 quadratic equation

The Attempt at a Solution

did each of these equations to get d=340m/s(3.7- 3.92) its wrong! PLEASE help :(

 

[Chi Meson]

Ttotal=trock+tsound distance=Vsound*tsound ts=340m/s-trock x=x+vt+.5at^2 quadratic equation

ts=d/340m/s

initial v is zero (simplify)
trock = SQRT (2d/g)

 

[afa]

I don't understand, what are you doing with the second equation?? can you go through the steps?