Answer:
Solution of a System. In general, a solution of a system in two variables is an ordered pair that makes BOTH equations true. In other words, it is where the two graphs intersect, what they have in common. So if an ordered pair is a solution to one equation, but not the other, then it is NOT a solution to the system.
I don't see any choices so I am going to give you what I think the answer would be. The rule would be 3x. That would be you could plug any number in and they would give you the sequence. Example:
x = 1
x times 3 = 3.
We could even find future things like:
x = 10
x times 10 = 30.
If we were doing it based on the algebraic expression it would be "multiplication" because we are multiplying. Hope this helped. :)