f(x) = -7x + 2
range = (-6,-2,6,19)
Replace f(x) with y
y = -7x + 2
The range is the output values, y
Replace y with each range value and
solve for x to get the domain.
-6 = -7x+2
-8 = -7x
8/7 = x
So the first point on your graph is (8/7, -6)
Do the same for the other 3 values on your range.
The domain will be the 4 values you obtain for x.