There are a total of 630 science and art books in the library, the ratio of the two books is 1:4, and some science and technology books are bought. At this time, the ratio of science and literature books to literature and art books is 3:7. How many?
图书室里有科技书和文艺书共630本，两种书的比是1：4，又买来一些科技书，这时科技书与文艺书的比是3：7，买来的科技书有多少？
<gadget id="calculator">1 + 4</gadget>
<output>5</output>

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

<gadget id="calculator">3 + 7</gadget>
<output>10</output>

<gadget id="calculator">7 / 10</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">(4/5) / (7/10)</gadget>
<output>8/7 = around 1.142857</output>

<gadget id="calculator">630 * (8/7)</gadget>
<output>720</output>

<gadget id="calculator">720 - 630</gadget>
<output>90</output>

<result>90</result>