The black rule says: The solution is easy, but not "easy".
The red rule says: The solution is simple, but not "simple".
The golden rule says: The solution is straightforward, but not "straightforward".
What is the solution?
All three of those words, Easy, Simple and Straightfoward, translate to "einfach" in German (The German flag being described by the colored rules), which I presume is the answer. Also, not sure if intentional, but a rule can be a type of line (see http://printwiki.org/Rule_Line or https://en.wikipedia.org/wiki/Ruled_paper), potentially meaning the "rules" are lines on the flag.
The German flag is composed of the colors black, red and gold.
If that is the solution, it's indeed straightforward, easy and simple, but I think there should be more to it.
The answer's already posted, but given the form of the question, I have to wonder if an alternate form of the solution is