To start off, simplify the equation if needed:
3m>=21
Since both sides are divisible by 3, you can simplify for the equation to be
m>=7
Next is to find the domain of the line graph. Since the sign is more than or equal to (>=), the circle is closed.
And since m is MORE THAN OR EQUAL TO, the section starts at 7 (closed circle), and continues after. Therefore, your answer will be the third selection.
