1
3h×60 min= 180min ×69sec =10 800 sec
45min×60 sec =2 700 sec
10 800 +2 700 +15=13 515 sec :60 = 225,25 min :60= 3,754 h
2h×60=120 min ×60= 720 sec
15 min×60= 900 sec
720+900+20=1 640 sec
1 640sec :60=27,33min :60= 0,45 h
2
12 510 s :60=208,5 min :60 = 3,475 h= 12 510 sec
8 430 s :60=140,5 min : 60= 2,341 h = 8 430 s