Circumference of the circle
cm
i.e., 
i.e., 
Area of the circle is given by




Therefore, the area of the circle is:

Divide by 3 and you get m^2-81 so then factor and get 3(m+9)(m-9)
The answer is GCF because you need to choose tha same number for both numbers and that number has to make both of them equal and the number is gonna be greater!