Using What-If modeling parameters

Hi All

I have a table where one column specifies the week as 1, 2, 3 etc. Another column specifies a job by specific code i.e. ABC-123, ABC-578, CCA-246 etc. And a third column showing how many hours are remiaining to be worked on that job. So if i took the difference between hours remaining on job ABC-123 from week 7 and week 11, I would know how many hours have been worked on that job in that timeframe. Likewise, if I took the difference of the total hours for all jobs in the same timeframe I would know how many hours have been worked total.

I am wanting to use the What-If parameters to set up two sliders so that I can select two different weeks on each slicer and it will give me the difference. For example if I set slider one to 3 and slider two to 7, it would show me the difference between hours for week 3 and week 7. 

I am having trouble figuring out how to code this out in Dax as the What-if peramiters are measures and my data is in columns. I hope I am just being foolish and this is easier than it seems.

Thanks

LilMurph