Suppose that 1 euro is worth $1.25. in europe, a book costs 19 euros. in los angeles, the same book costs $22.50. in which location is the book less expensive?

The book would cost less in Los Angeles because it would cost $23.75 in Europe.

Los Angeles location the book is selling is less expensive than in Europe.

In Europe the book costs 19 euros but we know 1euro = $1.25 
so 19 euro = 19 * $1.25 = $23.75
In Los Angeles the book only costs $22.50, $1.25 less than in Europe.