If |ax + b| = c|ax + b| either c = 1 or both c = 0 and ax + b = 0.
If c = 1: and c|ax + b| = c ---> |ax + b| = 1
then either ax + b = 1 ---> ax = 1 - b ---> x = (1 - b)/a
or -(ax + b) = 1 ---? -ax - b = 1 ---> -ax = 1 + b ---> x = (1 + b)/-a ---> -(1 + b)/a
If both c = 0 and ax + b = 0:
then ax = -b ---> x = -b/a