It's a linear function (y = mx + b, where m = -2 and b = 0).
The graph of that function is a straight line.
Therefore we need only two point to the plotting the graph.
y = -2x
We choose any two x values and we calculate the y values.
for x = 0 → y = -2(0) = 0 → (0, 0)
for x = 2 → y= -2(2) = -4 → (2, -4)
