Okay, here we have this:
Considering the provided equation, we are going to rewriting it into slope-intercept form. So we obtain the following:
6x+2y=6
2y=-6x+6
y=(-6x+6)/2
y=-3x+3
Finally we obtain that the equation of the line is slope-intercept form is y=-3x+3. Then replacing in y=mx+b, we have:
y=-3x+3
y=mx+b
Then, m=-3 and b=3.