Answer:
Sorry but your whole question is not here.
In medias res means to start a writing with events that happened in the middle of the story, then continuing the story from the beginning.
By definition, a business letter is used by employees and clients of different companies as a form of communication with regards to their agenda. In addition, it mainly comprises of tones having a much formal use of language. Proper formats must be observed in making these kind of letter such as avoid indenting when using a block format.