Hi there!
All sets of parallel lines must have the same slope, as this allows the line to go to infinity without intersecting.
In order to find the slope of 4x-3y=6, we need to put the equation in y=mx+b form. The m value will represent the slope.
4x-3y=6
-3y=-4x+6
y=4/3x-2
Therefore the slope would be 4/3.
Hope this helps!