The first step I took was to make a proportion. I did 9/21 equals x/100. The whole is 21 because it says "Hint: How many players did Clayton play/" so I am guessing it means adding 9 and 12. Then I divided 900 by 21 after using what you would call the butterfly method. I rounded 42.85... to 43.
I hope this helps. This is how I remember it and I got the correct answer. Good luck!
