Julia W. answered • 03/29/13

Algebra I Made Better

In Algebra, to undo an operation you perform the opposite operation.

and, remember--whatever you do to one side, you must do to the other side--

Thus you solve your equation--

3=3y-15

3+15=3y-15+15

18=3y

since you want y by itself, you undo the multiplication by 3

divide both sides by 3

so--

18/3=3y/3

6=y