If RunTime is in hours then one way:

E2: =D2 - C2/24

Format E2 the same ad D2.

In article ,
ShagNasty wrote:

Widget A operates 24/7 until failure. The time is in 24 hr format. Need to
substract C2 from D2 to get E2 (same format). I've tried several functions
and examples from the Discussion Groups. However; I need to see the (a)
correct answer for validation -- I get confused easily...

A B C D E
01 Equip RunTime EndDate&Time StartDate&Time
02 Widge A 8,939.9 03/15/08 12:54 ??/??/?? ??:??
03
04

ShagNasty...