Two boys who have the same weight are seated on one side of a see-saw, as illustrated. On the opposite side sits their father, whose weight is $1000\,\text{N}$. The see-saw is in balance and is used in a way that makes it move up and down. In one stage of the motion, the father moves downward by a distance of $40\,\text{cm}$. During that same time, the boy closest to the pivot moves upward by $20\,\text{cm}$, while the other boy moves upward by $80\,\text{cm}$. What is the weight of each boy?
- A$200\,\text{N}$
- B$400\,\text{N}$
- C$600\,\text{N}$
- D$800\,\text{N}$