First, put parenthesis around the first two numbers and the last two numbers. (20g³+24g²) (-15g-18) Then, take out the greatest common factor of both parenthesis. 4g²(5g+6)-3(5g+6) You then separate the numbers outside the parenthesis and the numbers in the parenthesis. (5g+6) (4g²-3) Then you simplify the second set of numbers. Since the set of numbers can't be simplified, you would leave this problem as it is. I hope this makes sense.