Answer:
Train A is 198 tons and Train B is 33 tons.
Explanation:
Take a system of equations where A+B=231 and A-B=165. If you line these up, you can use the process of elimination so you get 2A=396. Then, you divide both sides by 2. This gives you A=198. Then, subtract 165 from 198 and you get 33. Add 33 to 198 to get the original 231 tons given from the question.