Answer:
1780s to 1830s
Step-by-step explanation:
Pollution is not a new phenomenon. In fact, pollution has been a problem since the appearance of our earliest ancestors (Markham, 1994). Increasing human populations have opened the door to more bacteria and disease. During the Middle Ages, diseases such as cholera and typhoid fever broke out all across Europe.
If you find the least common multiple of both numbers, this will give you the information you will need to get your answer. Each revolution would include all teeth going around. The list of multiples for 24 are 24, 48, 72, 96, 120. The list for 40 are 40, 80, 120. This means at 120, they would be in the same place again. For the first gear to get to 120, it would take 5 rotations the fifth number in the list of multiples for 24). I hope this helps!
There you go!!! Hope I helped :)