Answer:
120960
Step-by-step explanation:
Given that a librarian has a set of ten different books, including four different books about Abraham Lincoln.
The librarian wants to put the ten books on a shelf with the four Lincoln books next to each other, somewhere on the shelf among the other six different books.
First arrnage the 6 other books in the shelf.
This can be done in 
Now arrange the 4 books of Lincoln
This can be done in 
Now we have 7 places to insert Lincoln books including two corners and in between.
Thus this can be done in 7 ways
Total no of ways = 
Answer:
L = 25 m
Step-by-step explanation:
L = 4W - 3
perimeter = 2(L + W)
64 = 2(4W - 3 + W)
divide both sides by 2:
32 = 5W - 3
add 3 to each side:
5W = 35
divide both sides by 5:
W =7
L = 4(7) - 3 = 25