Answer:
slope = -3
Explanation:
1) Rearrange eqn into slope intercept form
slope intercept form: y = mx + b
where...
m = the slope
b = the y-intercept (where the line crosses the y axis)
3x + y = 12
y = -3x+12
2) Know parallel rule. A line that runs parallel has the same slope but a different y-intercept
So the slope is: -3