Find the slope ($m$) and $y$-intercept ($b$) of the boundary line defined by $3x+6y=12$.

• A. $m=-\frac{1}{2}$, $b=2$
• B. $m=-3$, $b=12$
• C. $m=2$, $b=-\frac{1}{2}$
• D. $m=-\frac{1}{6}$, $b=12$

Answer: (A)