Given :
The slope of the line is m = -1/2
And y - intercept = b = 3
so, the slope intercept form of the line will be :

The standard form of the line has a general form like :

So, we need to convert the slope - intercept form to the standard form
It will be as following :

Multiply both sides by 2

Add x to both sides:

So, the standard form of the given line is:
x + 2y = 6