Each shelf of a bookcase contained 12 books. If the librarian took out 22 books and rearranged the remaining books so that all shelves but one contained 8 books and the last shelf contained 10 books, how many shelves does the bookcase have?	Choose the correct choice from the following choices: A) 8 B) 6 C) 7 D) 5 E) 4
Let x be the number of shelves.   No of books in the beginning =12*x   After taking out 21 books No of remaining books = 12x -21   when the remaining books are rearranged, each shelf except the last shelf has 8 books and the last shelf has 11 books. So No of remaining books is also equal to 8*(x-1)+10   12x-22=8(x-1)+10   4x=24   x=6. Answer 6
<result>B</result>
Each shelf of a bookcase contained 12 books. If the librarian took out 22 books and rearranged the remaining books so that all shelves but one contained 8 books and the last shelf contained 10 books, how many shelves does the bookcase have?