Step-by-step explanation:
We need only two points to the plotting a graph of a line.
for x = 0
[tex]y=\dfrac{1}{4}(0)-1=0-1=-1\to(0,\ -1)[/tex]
for x = 4
[tex]y=\dfrac{1}{4\!\!\!\!\diagup}(4\!\!\!\!\diagup)-1=1-1=0\to(4,\ 0)[/tex]