3/7
1) Let's pick those two points (3, -1) and (-4,-4) and plug them into the formula:
2) Since the slope is m = 3/7 and the line intercepts the y-axis. Let's find what point is that, plugging one point into the formula:
(3,-1)
y=mx+b
-1=3/7(3) +b
-1 = 9/7 +b
-1 -9/7= b
b =-19/7
y= 3/7x -19/7
3) A Parallel line have the same slope. So the answer is 3/7