This demo, done in Articulate Storyline 2, gives the student some math practice by using time. Here I incorporate JavaScript to manipulate the dates.

You will notice that all the calculations are relative to the current time. I have also tried to incorporate some randomness to the times, particularly in the first example.  If you come back to the first screen, it will update with a new time interval. I also use the random function in JavaScript to vary the position of the correct answer.