Stretch your thinking Carl's bookshelf has a for shelves with six books on each her brother with Robert has three shows with seven book on each they want to combine their books if they put 9 books on a shelf how many shells what they need

Oh, come on! Please post something that makes sense!

To find the total number of shelves Carl and her brother would need to combine their books, we need to calculate the number of books both of them have and then divide it by the number of books that can fit on each shelf.

First, let's find out how many books Carl has. She has 4 shelves, and each shelf has 6 books, so the total number of books Carl has is:

4 shelves * 6 books = 24 books

Next, let's find out how many books her brother, Robert, has. He has 3 shelves, and each shelf has 7 books, so the total number of books Robert has is:

3 shelves * 7 books = 21 books

To find the total number of books they have together, we add the number of books Carl has and the number of books Robert has:

24 books (Carl) + 21 books (Robert) = 45 books

Finally, to determine the number of shelves they need to combine all their books, we divide the total number of books by the number of books that can fit on each shelf (9 books):

45 books / 9 books = 5 shelves

Therefore, Carl and her brother would need a total of 5 shelves to combine all their books if each shelf can hold 9 books.