Answer: m = 6
Explanation:
First, we will rewrite this proportion:

Next, we will cross-multiply:
12 * 9 = 18 * m
108 = 18m
Lastly, we will divide both sides of the equation by 18:
m = 6
We can also solve this proportion another way.
We know that 18/9 = 2, so 12/m must equal 2 as well.
12/6 = 2, so m = 6.