Odpowiedzi

2009-12-17T19:18:43+01:00
5*45 + 3*10 + 15 = 225+45=270 minut
270:60 = 4h 30 minut

2009-12-17T19:20:35+01:00
45min*5+15min+10min*3=225min+15min+30min=270min= 4h 30min

odp: od pierwszej lekcji do ostatniej minęło 4godziny i 30 min:)
2009-12-17T19:22:24+01:00
(5*45min)-(3*10min+1*15min)=225min-30min+15min=180min=3godz