Two cars start moving from the same point. one travels south at 60 mi/h and the other travels west at 25 mi/h. at what rate is the distance between the cars increasing four hours later?

Oops, I missed they we're moving perpendicularly. Gotta be more careful.  I'm gonna blame this immovable answer box popping up and hiding the question on my browser. Plus I skimmed it.

We wont worry about the signs; they won't matter.  We have car 1  (x,y)=(0,60t) and car 2 (x,y)=(25t,0).  So the squared distance is

recognizing the Pythagorean Triple.  Everything's positive so

So they're moving apart at a constant 65 mph.

65 mph

54 kilometers per hour

step-by-step explanation:

according to rules:

1 km = 1000 meter

which means that 1 meter = 1/1000 km

1 hour = 3600 second [ as 1 hour = 60 min = 60 *60 seconds ]

which means that 1 second = 1/3600 hour

therefore, 1 kilometer/hour =

thus to convert 15 meter per second to kilometer per hour, we multiply 15 to 3.6 kilometer/hour.

15 meter/second=   which is the required answer.