The guy ran at a speed of 8.07783 MPH
Here's how I got my answer:
1 km/hr. = 0.621371
So, if you do
you will get your answer: 8.07783 MPH
The answer is 3. Divide 5375 by 4 to get 1343.75. Remainder for each friend is .75, so multiply .75 by 4. 3 cards left over.