A bookstore owner went to the wholesale market to buy some books.

Set the cost of a book as X yuan/book, spend 100 yuan, and buy 100/X books.

I bought 100/X+ 10 X+0.5 yuan for the second time, and spent a * * *.

(X+0.5)( 100/X+ 10)= 150

Simplify the equation and calculate it by formula method.

So X=2.5 or 2.

So 100 yuan bought forty or fifty copies.

Both answers are consistent with this question.

I bought 50 copies in 3 yuan or 60 copies in 2.5 yuan for the second time.

The 50% discount is 1.4, and they are all sold out. It must be a loss.

50 is a loss of 80.

60 has lost 66.