You basiclly divide 6 and 1.2 and get your answer.
The answer is C that is X=7 and X=-1
multiple x through the given equation to get rid of a fraction. It will be

After that bring 6X to the LHS of the equation
so that it will look like the general equation that is

Use the quadratic formula (or any other approach to find the values of x
You will arrive at

No, because there are TWO values of y for a certain value of x
say x=5, then y=2 and y=-2
That does not satisfy the concept of the function.