An oceanic depth-sounding vessel surveys the ocean bottom with ultrasonic waves that travel 1530 m/s in seawat

An oceanic depth-sounding vessel surveys the
ocean bottom with ultrasonic waves that
travel 1530 m/s in seawater.
How deep is the water directly below the
vessel if the time delay of the echo to the
ocean floor and back is 5 s?
Answer in units of m.

(1530 m/s * 5s)/2 = 3825 m

You divide by 2 because its two-way-time, and you only want one-way-time.

You can't do simple math?
.