The first time the shuttle fires is at 7:44:35:16 on Friday morning and the next time it fires them is in the wee hours at 2:26:33:07 on Saturday morning. How much time has elapsed between one firing and the next?
7:44:35:16 means hours:minutes:seconds:hundredths of seconds
in terms of Friday time, Sat at 2:26:33:07 = 26:26:33:07
So, just subtract
26:26:33:07
-7:44:35:16
to allow for borrowing, that's the same as
25:85:92:107
-7:44:35:16
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18:41:57:91