38 pages of the book will cost $57.
Data;
- number of page = 20
- cost = $30
To solve this question, we have to know the cost of one page of the book.
In the first scenario, 20 pages cost $30, let's find the cost of one page here.
We can confirm our answer here by testing with the second scenario;
Now can say that one page of the book cost $1.5, let's divide 57 by this to determine the number of pages
From the calculations above, 38 pages of the book will cost $57.
Learn more on proportions here;