The second choice is the answer
6/x=27
times both sides by x
6=27x
divide both sides by 27
6/27=x
2/9=x
the missing number is 2/9
I assume you are asking one of three things, so I will answer all of them.
if you are asking what is 1/2 of 312, then multiply 312 by 1/2. 312 is really just 312/1, so

we multiply fractions by multiplying straight across

if you were asking what part of 3 1/2 is 1/2 then we have to recognize what 3 1/2 is as an improper fraction. to do this, we convert 3 into halves. how many halves of pizza are there in 3 whole pizzas? 6. so we have 6 halves and one half, which is a total of 7 halves.

now, we do the same thing as the first problem

if you were asking what is half of 3.12, then we convert 1/2 to a decimal and multiply
Put 163 on top and then 66 on bottoms of the equation and then subtract. 3-6 u can't do so u barrow from the 6 and turn the 6 into a 5 and the 3 into a 13 then subtract 13 from 6 and get 7 then u can't subtract 5 from 6 so barrow from the 1 to make the 5 a 15 and the 1 to a 0 and then subtract 15 from 6 and get 9 and ur answer is 97!