a truck's tire has an outside radium of r inches. the area of the side of the tire not including inside rim is (pi)r^2-81(pi) inches whats the diameter of the rim

fill in blanks:

whole rim_________ rim:_________=(pi)r2
without rim= (pi)r^2-81(pi) r^2=________
rim= whole tire-without rim r = ________
=______ - (____)=______ d=2r___________




HELP PLEASE!!!!!!!!!!!!!!!!!!