My method is not the most common, but is correct:
Realize that if 2 lines are perpendicular, then the slope of one (call it "m") is the negative reciprocal of the slope of the other.
Solving 2y = 8x - 6 for y: y = 4x - 3. This has a slope of "m"=4, and so the slope of any line perpendicular to y = 4x - 3 will be -1/4.
Now we have the slope of the new line and know that this line passes through (-3,3). Use the point-slope formula here:
y-3 = (-1/4)(x-[-3]), or y-3 = (-1/4)(x+3)
