/ Thanks for your letter!/ Thank you very much for the letter you sent me.
-I’m sorry I haven’t answered earlier but I was really busy with my school/travelling/ ill
You asked me to tell you about… Well, …
By the way, Could you please tell me …?…? …? …?
Unfortunately, I’d better go now as I’ve got loads of homework to do (as always)/I should help my mother/ should walk with my dog. Take care and keep in touch!/ Drop me a letter a.s.a.p./Write back soon!
All the best,/Best wishes!/Lots of love,
Alex