Question

6,42h - 3h 56 min 54s

Answer 1

1h = 60 min 
60 m = 3600 sec 

6 h = 360 minute . 
0,42h = 42 minute => 6,42h = 402 minute . 

3h = 180 min 
180+56 = 236 min 54 sec => 402 min - 236 min 54 sec = 165 minute si 6 sec = 2h 45 min si 6 sec . Sper ca e bine , verifica daca nu cumva m-am incurcat la calcule .