One whale says something to its friend 75 km away . How long will it be before the friend can hear? The speed of sound in water is 1500 m/s

First, We convert 75Km in to meters . So, we have 75km = 75000 m. As we know that speed = Distance ? Time , we have , Time = Distance ? Speed. Therefore, from the question we have Time = 75,000 ? 1500 = 50 seconds.