Basically, all you want to do is this:
do 5 divided by 6 (calculator preferred so you don't do a ton of division)
you get: 0.833333333
You then do 0.833333333 * 12
Your Answer:
10

Shawaaaty

The answer is 10.
5/6 = x/12
x= the missing number
Since, 6 times 2 is 12. You have to multiply 5 by 2 too. So, your answer is 10.