Help Adding Time

I have a project where I need to ADD TIME. Under normal circumstances, it wouldn't be a problem. However, in some cases, I may need to have totals that exceed 24 hours. So, I need 2 forumlas.

First, I need a formula that will add the total time in hours taking into account the start/end dates.

Second, I need a formula that will add all the resulting hours.

Keep in mind that this EXAMPLE is very minimal and I may have 70 line items.

Can anyone help me out here?

Thanks!

Someone helped me with the foumula which ended up being:

=IF(OR(A2="",C2="",C2-A2+D2-B2

This formula successfully takes into account both the date and the time and resulting in hours/minutes, just as I wanted.

However, I have another problem. That's with ADDING all the time in column "E".
The problem is that when I use: =SUM(E2:E8) in this example, the addition works just fine. But, when I try to add up 40+ cells, I get some crazy number that's only a fraction of the actual sum.

Any ideas?