How are the respiratory system and the circulatory system connected?

The respiratory system works directly with the circulatory system to provide oxygen to the body. Oxygen taken in from the respiratory system moves into blood vessels that then circulate oxygen-rich blood to tissues and cells.

Explanation:

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      x/140 = 25/100

we need to find the x to find the x multiply 140 and 25

and what do you get 3500.   and what is 3500 divided by 100

= 35