How do I Visual Countdown Timer using dt

So, sometimes you get stuck on these simple solutions, shows how much you followed along in Math class Anyways please help, Im seriously stuck on this one.

I want to make a green line around 100 pixels long, a counter cTimer will start on 30 seconds. How would I go abouts making the line count down every step for 30 seconds until it is gone?

Thank you in advance.

Think you need to do 30/100 *10 - cTimer and remove that value from the line but am stuck here on the calculations Like I said I know its dead simple I just have a brain lock atm....

Why would you use dt instead of the timer behaviour or the wallclock, which count in seconds?

You will find all the demo tutorial at link below

https://www.dropbox.com/sh/eioscti86bpr ... 7YPza?dl=0

Many thx guys. I didnt know about the wallclock or timer behaviour, just read about dt everywhere when you search for timer on forums hehe