Y=mx+b
parallel lines will have the same slope.
using the points (-4,6) and the slope for the parallel line -3 we can find b (the y intercept) for the line.
6 = (-3)(-4) + b
6 = 12 + b
-12 + 6 = -12 + 12 +b
-6 = b
so the line that runs through points (-4,6) and parallel to y= -3x+4 is:
y = -3x -6