Bonjour,
1)
3,2 h = (3 + 0,2) h = (3 + 2/10) h = 3 h + 2/10 h = 3 h + 2/10 x 60 min = 3 h + 120/12 min = 3 h 12 min
5,6 h = (5 + 0,6) h = (5 + 6/10) h = 5 h + 6/10 h = 5 h + 6/10 x 60 min = 5 h + 360/10 min = 5 h + 36 min
7,75 h = (7 + 0,75) h = (7 + 75/10) h = 7 h + 75/10 h = 7 h + 75/10 x 60 = 7 h + 450/10 min = 7 h + 45 min
2)
54 km/h = 0,9 km/min = 15 m/s
36 km/h = 10 m/s
80 m/s = 4,8 km/h
