The standard form of the equation of a line is ax + by = c, where a b and c are integers.
You are given a slope of m = 1/2 and b = 3. Note that m is used in the slope intercept form of a line, so let's first express this using slope intercept form of for a line, which is y = mx + b.
Plugging in given values you get
y = (1/2)x + 3.
Standard form requires coefficients to be integers, so multiply both sides by 2 to get rid of the fraction.
2y = x + 6
Finally reorder the terms. Subtract both sides by 2y then subtract both sides by 6.
x - 2y = -6