A Locomotive Is Pulling Three Wagons Along a Level Track

A locomotive is pulling three wagons along a level track with a force of 100,000 N. The wagon next to the locomotive has a mass of 70,000 kg, the next one, 50,000 kg, and the last one, 80,000 kg. Neglect friction. What is the force between the 80,000-kg and 50,000-kg wagons?

A) 35,000 N
B) 40,000 N
C) 50,000 N
D) 60,000 N
E) 65,000 N