Some important things to note when writing a formal letter are:
You should note that your letter should be well written and should communicate your points clearly.
Make some suggestions about what should be done so that travellers on the metro train would feel safer while travelling and how to eliminate the pickpockets and other undesirables in the train station.
You should end your letter stating your full name.
Read more about formal letters here:
https://brainly.com/question/959565