Slope intercept form is y = mx + b. M is the slope and B is the y-intercept.
The first step would be to subtract 9x from both sides. This leaves you with -3y ≥ -9x + 12.
Next, you would divide both sides by -3. This gives you y ≤ 3x - 4. Make sure you flip your sign from ≥ to ≤ because you divided by a negative number.
Your inequality in slope intercept form is y ≤ 3x - 4