The breaking point is at 2. So draw a thin vertical line at x=2,
so you can erase it later:
Get a couple of points using values of x which
are greater than 2 and use f(x) = -x:
x | f(x)
3 | -3
4 | -4
Connect those points just up to the green line:
--------------------------------------------
Get a couple of points using values of x
which are less than 2 and use f(x) = x-4:
x | f(x)
-2 | -6
1 | -3
Connect those points just up to the green line:
Erase the green lins:
Edwin