First convert seconds to minutes by diving by 60,
[tex]23040/60=384[/tex]
Then add these minutes to the minutes you already have,
[tex]384+384=768[/tex]
Now divide minutes by 60 to get hours,
[tex]768/60=12.8[/tex]
But since 0.8 hour can be converted to minutes, multiply 0.8 by 60 to get back the minutes for this decimal part,
[tex]0.8\cdot60=48[/tex]
Now put the data together,
[tex]12\mathrm{h}\: 48\mathrm{min}[/tex].
The answer is [tex]384\mathrm{min}\: 23040\mathrm{s}=\boxed{12\mathrm{h}\: 48\mathrm{min}}[/tex].
Hope this helps :)
