Answer:
1.65 minutes
Step-by-step explanation:
10 9/10 + 5 3/5 = 16 1/2
16 1/2 divided by 20 = 1.65 or 33/20
2 hours × 60 km/hour = 120 km
390-120 = 270 km remaining
270 km/(3 hours) = 90 km/hour
2 2/3
hope i helped. (: