What kind of education is required to be a ocean engineer?

i had this question and the answer was 3.15 miles.

martina travels from school to her mom's office. from there, she walks to school. after school, she walks to the library and then to a friends house before finally ending back at home. find martina's total distance traveled.

a) 0 miles  

b) 0.4 miles  

c) 1 mile  

d) 3.15 miles

if the person is shown to have +90n, then ans is -10n.

if the person is shown to have -90n, then ans is +10n.