Answer:
There are 154,440 ways.
Step-by-step explanation:
The word arrange means that the order in which the books are placed is important, which means that the permutations formula is used to solve this question.
Permutations formula:
The number of possible permutations of x elements from a set of n elements is given by the following formula:

In this question:
5 books from a set of 13. So

There are 154,440 ways.
let the original price be x.
then,
x- 25% of x= 24
x- 25x/100 = 24
x- x/4=24
3x/4=24
3x= 96
x= 32
in short...the original price= 32 dollars
3/8 = 0,375
0,375 * 100% = 37,5 %
This is the Equation: 2x + 6