US paper currency has changed greatly over the last 30 years - much more than in the 100 previous years. Why?

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

one person pulls 90n one way and the other has 100n pulling the other way.

so the net force = 90 - 100 = -10n,

or the ans can be 10n if the picture shows -90n and 100n instead.

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

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

distance = 150m

displ = root (50 ^2 + 100^2)

root(2500+10000)

root 125000