I have 3 columns of times in the hh:mm:ss format. The first column (A1) is
time recieved, the second is time staged (A2, usually blank), and the third
(A3) is time arrived. Is it possible to have a formula that will calculate
elapsed time like:

In A4 (if A2 is not blank than - A1, if it is blank than A3-A1)

I have tried many different examples that I have found on here, but with no
luck. Thank You!!
--
Daniel