If the 10 books are all different, we have:
• 10 ways of selecting the first book,
,
• 9 ways of selecting the second book,
,
• 8 ways of selecting the third book,
,
• 7 ways of selecting the fourth book.
The total number of ways to arrange 4 of the 10 books is:

Answer
There are 5040 ways of arranging the books.
As the value of X increases, the value of y would decrease, due to this relationship being an inverse variation. ... An inverse variation would be similar to a linear relationship because in both, values can increase, as others decrease, and it would pretty much be it, because there aren't much similarities between them.
Answer:
13 - 4x = 1 - x
Subtract 13 from both sides.
-4x = -12 - x
Add x to both sides.
-3x = -12
Divide both sides by -3.
x=4
:)