What property can we use to isolate the variable, f

To isolate variables you can either:

- subtract from both sides

- add to both sides

- multiply both sides (by the same number)

- divide from both sides

These were basic.

Some more advanced ones are:

- raise both sides to the same exponent

- root both sides by the same root.

It has to be an inverse operation however, for all of these properties. And remember, they only work because they are done to both sides.