There are 210 books in the class book corner, among which new books account for (5/7). After another new book is added, the ratio of the number of new books to the number of existing books is 4:5. How many new books are there?
班级图书角有210本图书，其中新书占(5/7)，又进一起新书后，新书的本数与现有的图书本数的比是4：5，现有新图书多少本？
<gadget id="calculator">5 / 7</gadget>
<output>5/7 = around 0.714286</output>

<gadget id="calculator">1 - (5/7)</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 - (4/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(2/7) / (1/5)</gadget>
<output>10/7 = around 1.428571</output>

<gadget id="calculator">210 * (10/7) * (4/5)</gadget>
<output>240</output>

<result>240</result>