Reviewing for a algebra one exam!
I'm sure you meant y = 1/2 x + 3
If that's the case then you would follow these steps.
First you will need to eliminate the fraction by multipling everything by 2.
2(y) = (1/2)(2)(x) + 3(2) which in turn equals
2y = x + 6
Now we need to put both the x and y on the same side by subtracting x from both sides
2y - x = x - x + 6 which equals
2y - x = 6
Standard Form is Ax + By = C so rearrange the problem to
-x + 2y = 6