A Locomotive Is Pulling Three Train Cars Along a Level

Short Answer

A locomotive is pulling three train cars along a level track exerting a force of 100,000 N.The car next to the locomotive has a mass of 80,000 kg,the next one,50,000 kg,and the last one,70,000 kg.You can neglect the friction on the cars being pulled.
(a)What is the magnitude of the force that the 80,000-kg car exerts on the 50,000-kg car?
(b)What is the magnitude of the force that the 50,000-kg car exerts on the 70,000-kg car?