Marcella lives 7.1 miles directly west of school. Enrico lives 6.3 miles directly east of school. How far do they live from each other?

Since they live in the opposite directions of each other, you need to add the number of miles that each of them live away from school and add them together.

7.1+6.3=13.4 miles away from each other

Answer: 13.4 miles away from each other

if they live straight across each other then you have to add 7.1 and 6.3 because those are the start of the same destination. 7.1 + 6.3 is13.4