The answer to this question is 8-2.
To solve this we need to use this formula:
a(b+c)=ab+ac
5(7+3x)-12=35+15x-12=15x+23
Ok sure! Let's start with the marbles first. We have one red one blue and one green. There is a red and a blue cube. All we do is list the possible combinations of one marble and one cube. The answer would be : 1 blue marble, 1 blue cube. 1 red marble, 1 blue cube. 1 green marble, 1 blue cube. Then again but with the red cube. So in all, there are 6 possible combinations. Hope this helps. ☺️