2x = 15 + x
First, our goal is to get 'x' to equal something by itself. To do so, we will have to do everything on one side. Let's subtract 'x' from each sides.
[tex]2x - x = 15[/tex]
Second, our next step is to subtract '2x - x'. Since 'x' is basically considered (1), it will equal 'x'.
[tex]x = 15[/tex]
Answer: [tex]\fbox { x = 15 } [/tex]
