What are these +2's and +3's used for in solving first-degree equations?

[Tregg Smith]

I'm brushing up on algebra. In the second line what are these +2's for ? I couldn't get all the columns to line up. BTW does anybody know any software for writing down math problems that solves this alignment problem?

Solving first-degree equations

3x-2=16
+2 +2 what are these +2's ?
3x=18

3x = 18
3 3

x=6

 

[Mark44]

I'm brushing up on algebra. In the second line what are these +2's for ? I couldn't get all the columns to line up. BTW does anybody know any software for writing down math problems that solves this alignment problem?

Solving first-degree equations

3x-2=16
+2 +2 what are these +2's ?
3x=18

3x = 18
3 3

x=6

The 2's are shown to indicate that 2 is being added to both sides of the equation. Similarly, the 3's indicate that each side is being divided by 3.

Starting from any equation, if you add the same quantity to both sides of the equation, you get a new equation with the same solution set. Also, if you multiply or divide both sides of an equation (you can't divide by zero, though), the new equation has the same solution set as the previous equation.