Dear Davie,
i'm very glad to receive your letter telling me about your troubles. You said (他的烦恼）,I feel sorry about this. My suggest is that you should first……, second.(你的建议）. Besides, you ought to do your best to improve your study, because you can benefit a lot from your hard-working. I hope these suggestions can be helpful to you. Best wishes.
Sincerely yours,
Lingling