Answer:
2.5 hours (2 hours 30 Mins)
Step-by-step explanation: I used division to divide the miles according to the hours. I found a pattern to help discover answer. This does not always work but in this case it did !
15min*************************10 miles
30min*************************20 miles
1 hour************************40 miles
1hour30min****************60 miles
2hours**********************80 miles
2 hour30min**************100 miles
3 hours*********************120miles
