What is the greatest common factor of (a2−9) and (3a2−3a)?
It should be 3a notice that you can open (a^2-9) into a (a + 3 ) x (a - 3 ) and (3a^2-3a) into 3a ( a - 1 )
It should be much easier to recognize the gcf in both equations once you open them up
+122 
