Answer:
74 mph
Step-by-step explanation:
The driver started driving at s mph.
After 3 hours, the speed became s + 10 mph.
The total time is 11 hours, so 3 hours were driven at s mph and 8 hours were driven at s + 10 mph.
speed = distance/time
distance = speed * time
distance = (distance driven at speed s) + (distance driven at speed s + 10)
894 = s * 3 + (s + 10) * 8
3s + 8s + 80 = 894
11s + 80 = 894
11s = 814
s = 74
Answer: 74 mph
