Can anyone help me with this problem?

I am making a table that will calculate hrs worked. Column B has the hr started. Column C has the end time. Note - the start time can be in the evening and the end time can be in the am of the next day - giving me a negetive number.

I would need the easiest way to find the time difference between the two. This would be my column D. I would then need to add these two columns up to figure the total number hrs worked...

Thanks!