Respuesta :

60 x 60 = 3600 (1 hour)
60 x 30 = 1800 (half hour)
3600 + 1800 = 5400 for one and half hour
answer C. 5400
For one minute: 60 times
for 60 minutes(1hour): 60*60=3600 times
for 90 min: 60*90=5400 times