A submarine descended 3/5 of a kilometer in 1/5 of an hour. What was the submarine’s rate of descent in kilometers per hour?

Answer:3 km per hourStep-by-step explanation:You can deduct the answer instinctively since both the distance and the time of the descent are expressed in /5... so you can just get rid of the '/5' in both instances to get the result: 3 kilometers in 1 hour.But you can also find it easily using the cross-multiplication system:[tex]\frac{3}{5} km  =  \frac{1}{5}  hour[/tex]Then you multiply each side by 5 to get3 km = 1 hourThus the rate of descent is of 3 km per hour.