a)
4:23 → 5:00 → 37 min
5:00 → 7:00 → 2 h
7:00 → 7:11 → 11 min
37 min + 2 h + 11 min = 2 h 48 min
b)
23:37 → 00:00 → 23 min
00:00 → 13:00 → 13 h
13:00 → 13:15 → 15 min
23 min + 13 h + 15 min = 13 h 38 min
c)
13:18 → 14:00 → 42 min
14:00 → 19:00 → 5 h
19:00 → 19:38 → 38 min
42 min + 5 h + 38 min = 5 h 80 min = 6 h 20 min
