A bookstore purchased 200 books last month. Half of the books were sold for $10, at a gain of 25%, and the rest of the books at a loss of 10%. What is the total cost for the 200 books if the bookstore neither gained nor lost on the deal?

dollars

The cost of the first 100 books: 100 × $10 ÷ (100% + 25%) = $800

The gain of the first 100 books: $800 × 25% = $200

The loss = The gain = $200

The cost of the rest of the 100 books: $200 ÷ 10% = $2000

Total cost = $800 + $2000 = $2800

So the answer is $2800.