To put a slope-intercept into standard form, you have to first cancel out the fractions. So:

Turns into:

Simplify:

Distribute:

Since you want to get x and y on the same side, you subtract 12x from both sides to get:

So, your answer is
C. Hope this all made sense! If it doesn't you know where to get a hold of me, so just dm me. Or if you more problems.