e=vt (espace parcouru = vitesse x temps)
t=e/v
6) a) t=480/120=4h ; b) t=720/60=12h ; c) t=70/40=1.75h=1h45mn ; d) t=100/12=8.33...33h=8h20mn ; e) t=5000/340=14.7058824h=14h42mn21.18s
7) a) t=5/10=0.5h=30mn ; b) t=20/5=4h ; c) t=1000/12=83.333.333h=83h20mn ; d) t=0.1/40=0.0025h=9s ; e) t=10000/340=29.4117647h=29h24mn42.353s
