WW2 I believe/think. That would be my answer.
Answer:
A market for cats would have had a positive externality.
Because the cats would kill the rats on sight since that is their natural behavior.
However, it is interesting to mention, that the cat's killing has been more of a "mythic" aspect of this story, since it fails to take into account that since the black death was caused by the<em> yersinia pestis</em> bacteria, cats could have been also infected, and since their interactions with humans are greater than rats or fleas, the real outcome could have been totally unexpected.
So the equation would be 500 km ÷ 10 km/h = 50 (500÷10=50) Therefore your answer is 50
In the UK, he was called "Slater the Traitor" because he brought British textile technology to America, modifying it for United States use. He stole the designs of textile factory machinery as an apprentice to a pioneer in the British industry before migrating to the United States at the age of 21.
Source - Wikipedia
