a)
12 hours 24 minutes + 3 hours 18 minutes = 15 hours 32 minutes
14 hours 26 minutes - 5 hours 42 minutes = 13 hours 86 minutes - 5 hours 42 minutes = 8 hours 44 minutes
b)
5,4 hours + 11,2 hours = 16,6 hours
20,4 hours - 12,8 hours = 7,6 hours
a)
12 hours 24 minutes + 3 hours 18 minutes = 15 hours 32 minutes
14 hours 26 minutes - 5 hours 42 minutes = 13 hours 86 minutes - 5 hours 42 minutes = 8 hours 44 minutes
b)
5,4 hours + 11,2 hours = 16,6 hours
20,4 hours - 12,8 hours = 7,6 hours