Answer:
The price of the book is $7.75.
Step-by-step explanation:
Let's first establish an equation.
If I buy a book costing [tex]x[/tex] dollars and a bookmark costing 1 dollars, I will have spent [tex]x + 1[/tex] dollars. So a group of 15 people doing the same will have spent [tex]15(x+1) = 15x + 15[/tex] dollars.
Analogously, the group of 3 people has spent [tex]3(x+36) = 3x + 108[/tex] dollars.
Since we know that both groups spent the same amount of money, we can set the two expressions equal to each other:
[tex]15x+15=3x+108\\12x=93\\x=7.75[/tex]
Because [tex]x[/tex] was the price of the book, which was asked for in the question, we conclude that the answer is $7.75.
