This small project is created as answer to a question on the Adobe forums. You can visit the thread using this link:

https://community.adobe.com/t5/captivate/when-clicked-plus-minus-button-the-red-box-should-move-to-left-right/td-p/11159710?page=1

You will see that the user was using a ‘outdated’ workflow with a multitude of Show/Hide actions and decisions in conditional actions, probably based on equally outdated tutorials which were published before the Multistate objects appeared.  Have a look at this sample project. It has only one slide. Use the Minus and the Plus button to move the slider. There is a protection based on the limits. The text ‘slider…’ to start with zero.

Tow multistate objects (progress bar and Text warning) , two variables and two one-decision advanced actions have been used. If this slider would be reused often, maybe with a different set of  states, I would convert the advanced to shared actions of course.