The correct answer is b) 3(3x - 2)
In order to factor this, you have to find the greatest common factor of 9x and 6. Since 6 does not have an x in it, we cannot pull out an x. Instead we have to look for the biggest whole number that goes into 9 and 6, which is 3.
Next, to take the 3 out, we need to divide each term by 3.
9x/3 = 3x
-6/3 = -2
So the 3 comes out and the results above go together in the parenthesis.
3(3x - 2)
