Formal or Informal? Sort the Letter Phrases

Formal or informal?

Would you write this to a hotel manager or to your best friend? Drag each card into the right box.
Formal
Sorry I haven't written for ages.
Hi Jess!
I am writing with regard to your advertisement in The Times.
Dear Sir or Madam,
Thanks for your letter – it was great to hear from you!
I am writing to enquire about your summer courses.
Further to our phone call yesterday, I am sending you the form.
Guess what? I've got some big news!
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Informal
Tip: formal letters use full forms and set phrases, informal letters sound like talking.

Every card here belongs to either a formal letter or an informal one. Drag it into the right box: a card dropped in the wrong box comes back, so each round ends with a correct sort. Round 1 is about starting a letter, round 2 about the main part and round 3 about endings.

Formal letters use full forms (I am, I would), polite set phrases and no slang. Informal letters sound like talking: contractions, questions to the reader and phrases like Guess what? or By the way.

Leave it if you want an answer.