Answer:
Hailey walked 70 miles last month.
Explanation:
Consider the provided information.
Hailey walks at an average rate of 3.5 miles per hour.
She walked 3 weeks at her regular rate for 6 hours per week.

Hence, she walk 63 miles in last 3 weeks.
She walked 1 week at one-half her regular rate for 4 hours.
Half of her regular rate is

Therefore, the distance covers

The sum of distance is: 63+7=70
Hailey walked 70 miles last month.