Convert Standard Form into slope-intercept form:

3x+by=12

y = (-3/b)x +12/b

**Slope** of parallel lines is negative reciprocal of this slope (-3/b):

y = (b/3)x + C [**note:** y-intercept is different,;**not 12 **]

and we need point (4,9) to find C **[note: we must use y=mx+C because b is already used.]**

0 = (b/3)(4) + C

-4b/3 = C

so, the parallel line is:

** y = (b/3)x - 4b/3 [ also **y = bx/3 - 4b/3 ]