If x = 2z, then what is the circumference of the pie?

where is X located?

Green, because ants don't wear hats on Thursday.

This website will give you a good answer  http://www.mathgoodies.com/search/Default.asp?zoom_query=If+x+%3D+2z%2C+then+what+is+the+circumference+of+the+pie%3F&x=45&y=27