Final answer:
Marty walked 3.5 miles to school.
Step-by-step explanation:
To find out how far Marty walked, we first need to determine the total distance he traveled.
It is given that the distance from home to school is 7 miles.
Marty walked halfway to school, which means he covered half of the total distance.
Half of 7 miles is 7/2 = 3.5 miles. Therefore, Marty walked 3.5 miles to school.