Add 10 to the numerator of (2/7), how much should be added to the denominator to keep the size of the fraction constant
把(2/7)的分子加上10，要使分数的大小不变，分母应加上多少
<gadget id="calculator">2 + 10</gadget>
<output>12</output>

<gadget id="calculator">12 / 2</gadget>
<output>6</output>

<gadget id="calculator">7 * 6</gadget>
<output>42</output>

<gadget id="calculator">42 - 7</gadget>
<output>35</output>

<result>35</result>