Răspuns:
76.800+63.420=140.220
explicatie:
21h 20m = 76800sec. h=3600s
17h 37m = 63.420sec m=60s
21*3600=75.600
20*60=1.200
75.600+1.200=76800
17*3600=61.200
37*60=2.220
61.200+2.220=63.420
Sper ca te-am ajutat!