Réponse :
Bonsoir
Explications étape par étape
30s + 30s = 60s = 1 min
30 min + 30 min = 60 min = 1 heure
1 min 20s + 40s = 1 min + 60s = 2 min
1 h 30 + 1 h + 30 = 3 heures
1 min 40s -30s = = 1 min 10s
2 h 15 min -10 min = 2 heures 5 min
45s + 60s = 105 s = 1 min 45 s
35 min + 45 min = 80 min = 1 h 20 min
1 h 50 min + 15 min = 1 h 65 min = 2 h 5 min
2 h 50 min + 30 min = 2 h 80 min = 3 h 20 min
1 min -40s = 20s
2 h - 30 min = 1 h 30