Dear [Имя друга],
Thank you for your email. It was great to hear from you again. I haven't written for so long but I was busy with my school. In your letter you asked me about [тема письма] (тема – указана в задании subject).
Well, (отвечаем на вопросы ПОСЛЕДОВАТЕЛЬНО!)
Write back soon.
Best wishes,
[Твоё имя]
6 класс - объем 60 - 70 слов.