(4/5) Add 10 to the denominator, the size of the fraction remains the same, how much should be added to the numerator
(4/5)分母加上10，分数的大小不变，分子应该加上多少
<gadget id="calculator">5 + 10</gadget>
<output>15</output>

<gadget id="calculator">15 / 5</gadget>
<output>3</output>

<gadget id="calculator">4 * 3</gadget>
<output>12</output>

<gadget id="calculator">12 - 4</gadget>
<output>8</output>

<result>8</result>