Your younger brother has fallen into bad company. Write a letter to him, advising him to give up bad company and take more interest in studies.
35, Nizamuddin East,
I have learned that you have fallen into bad company. You have developed bad habits like drinking and smoking. The Progress Report of your House examination is here before me. You have failed miserably in almost every subject. The Principal of your school has remarked that you must mend your ways immediately.
Dear Mohan, Papa, and Mamma are really pained to learn all this. As such I as your elder brother sincerely advise you to give up bad company and take more interest in studies to show better results, otherwise, it will be too late and you may have to repent in life.
Loves from self, Papa and Mamma.