??
Simple.. I think..
You just divide.
x=3
x=6 because you have to always have a 2x if the y is all by itself on the other side of the equation.
You cannot say what 'x' is with just this one equation....you either need a value for 'y' or another equation relating 'x' and 'y' This equation is a LINE of solutions.
(y= mx + b....remember?)
~jc
