Ao Zebra and Koizumi share several books, among which Ao Zema's book belongs to Koizumi (3/5). Later, Koizumi gave Ao Zema three books, so Ao Zema's book belongs to Koizumi (5/7). So how many books does Koizumi have?
奥斑马与小泉共有若干本书，其中奥斑马的书是小泉的(3/5)，后来小泉给了奥斑马3本书，这样奥斑马的书是小泉的(5/7)．那么小泉原有多少本书？
<gadget id="calculator">5 / 7</gadget>
<output>5/7 = around 0.714286</output>

<gadget id="calculator">1 + (5/7)</gadget>
<output>12/7 = around 1.714286</output>

<gadget id="calculator">(5/7) / (12/7)</gadget>
<output>5/12 = around 0.416667</output>

<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">1 + (3/5)</gadget>
<output>8/5 = around 1.6</output>

<gadget id="calculator">(3/5) / (8/5)</gadget>
<output>3/8 = around 0.375</output>

<gadget id="calculator">(5/12) - (3/8)</gadget>
<output>1/24 = around 0.041667</output>

<gadget id="calculator">3 / (1/24)</gadget>
<output>72</output>

<gadget id="calculator">1 - (3/8)</gadget>
<output>5/8 = around 0.625</output>

<gadget id="calculator">72 * (5/8)</gadget>
<output>45</output>

<result>45</result>