(8, 7), (6, 9, 10, 5) (how many, 13)
(8，7)，(6，9,10，5)(多少，13)
<gadget id="calculator">5 - 13</gadget>
<output>-8</output>

<gadget id="calculator">10 + (-8)</gadget>
<output>2</output>

<result>2</result>