He will not get any benefit from the sales of book.
He will not get any benefit from the sales of the book.
My question is how to use articles in noun phrases. "Sales of book" I consider as a one noun phrase. Therefore I use "the" before the phrase, but in the second sentence I use "the sales of the book" as an online sentence checker interprets the first question as an error.
The second question is: when I write two nouns together and one is countable and other is uncountable, what is the rule for of the use of the article in this case? My concept is that i will use the article according to the meaning of the two nouns together in a sentence and a phrase like "finance department" will be considered as an countable noun.