When trinity pulls on the rope with her weight, newton's third law of motion tells us that the rope will

As we know that for every action there is equal and opposite reaction

So here it says that if we apply some external force on a system then system will exert same magnitude force on us but in opposite direction.

This is Newton's III law which is applicable in all classical situations

Now here we can see in the given situation we have given that Trinity pulls the rope with her weight so As per Newton's III law the rope will Pull Trinity by same force i.e. equal to his weight in opposite direction.

the total distance that martina travels that day is

(distance from home to mom's office) plus (distance from mom's office to school)

plus (distance from school to library) plus (distance from library to friend's house)

plus (distance from friend's house to martina's house).

(we don't know what any of these distance actually is.)

conservation of mass

mass before something happens = mass afterwards