Make a button appear when a condition is met

Hi Tom. Thanks so much for responding. I want to make sure I'm doing this correctly.  At the end of each optional module, I create a trigger:

a) Action - Adjust Variable

b) Variable - Add value 1 to "variable name"

c) When -  Timeline ends on  This slide (this slide being the last slide of each module)

THEN to trigger the FINAL EXAM button to appear on the menu page do I????

a) Change state of "Button" to Normal

b) When "variable name" changes 

c) If condition "variable name" = value 2

Or is there a better way to hide the button initially and have it appear when the condition of "value 2" is met?