Answer: She walks for 1 hour and 45 minutes
Explanation:
If she walks 2 miles in 30 minutes, that means she walks 1 mile every 15 minutes, and she walks 4 miles in an hour, that would mean that for every 15 minute interval, you can add 1 mile.
7x15=105=1.75
1.75 hours is 1 hour 45 minutes.