(Note: this is hard to explain without graphing. You might want to graph both of these lines just to make sure I did this correctly. :))
Y = -4(x) is the y = mx + b where m = slope and b = the y intercept.
So the slope of line A is -4 / 1 and the y intercept is 0. (If it's 0 there is no point in writing it down, so it was left out of the equation.)
The slope of line B with be equal to the slope of line A, so we can fill that in our equation. y = -4 x + ??
We know that y increases as x decreases.
Now we just need to scale 8, -3 down until x = 0.
(8 - 4, -3 + 1) = (4, -2)
(4 - 4, -2 + 1) = (0, -1)
y = -4x -1 is your final answer. Hope that helps! :)