Calculating Water Depth Using Sound Waves

[Douna2nd]

Homework Statement

a submarines sends sound waves and receives it after 4 seconds then goes under water 700 m and sends waves and receives it after 3 seconds he wants the depth of water

Homework Equations

V=d/t

The Attempt at a Solution

V=d/t V=x/2
then V=X-700/1.5 so x/2 = x-700/1.5 and X = 2800 is this right ?

 

[voko]

I did not understand you derivation, particularly the V = x/2 part, but the result is correct.