(твой город)
Russia
20/05/2017
Dear Mary,
Thank you for your letter. I received it yesterday.
I'm proud of you for getting such good marks! Great you are!
As for me, I usually get good marks like 4 and 5. To tell you the truth, I worry about my school marks because if I have bad marks, it will spoil my certificate, you know...I definitely worry about my future exams, I think it is the main part of our education and everyone should prepare for them and pass successful!
Now, it`s my turn to ask you some questions.
What are your summer plans? Will you come to see me? How do you prepare for your exams?
That`s all for now.
Write soon.
Best wishes,
(твое имя)