Im not sure how to do this or if I do any calculations, please help and thanks if you can!

Although respiratory organs vary across different organisms, they all contain respiratory surfaces that have a large surface area and are extremely thin. explain why having an extremely thin respiratory surface with a large surface area is advantageous for the process of gas exchange

Ineed ! i have no clue how to do this problem.

What causes most sediment to wash or fall into a river