To get this answer you have to multiply 9 and 12 which would be 108. Then you have to divide 108 on both sides to get mm by itself. 756 divided by 108 is 7 which is the answer!
The answer is seven (7) because 9 times 12 = 108 so you have to figure out hmmmmm what factor can you get to multiply something with 108 to get to 756 so you divide:) after that you'll get 7
