Xinhua Bookstore sold 40 copies of "Harry Potter" and "Lord of the Rings" in one day, among which "Harry Potter" was 30 yuan each, and "Lord of the Rings" was 25 yuan each. According to statistics, the income from selling "Harry Potter" is 650 yuan more than that of "Lord of the Rings". How many copies of "Harry Potter" were sold on this day?
新华书店一天内卖出了《哈利波特》和《魔戒》共40本，其中《哈利波特》每本30元，《魔戒》每本25元．经过统计，卖《哈利波特》的收入比《魔戒》多650元，这天卖出多少本《哈利波特》？
<gadget id="calculator">1_000 + 650</gadget>
<output>1_650</output>

<gadget id="calculator">30 + 25</gadget>
<output>55</output>

<gadget id="calculator">1_650 / 55</gadget>
<output>30</output>

<result>30</result>