Subtrahend + subtrahend + difference = 104, where the subtrahend is 40, what is the difference.
被减数+减数+差=104，其中减数是40，差是多少．
<gadget id="calculator">104 / 2</gadget>
<output>52</output>

<gadget id="calculator">52 - 40</gadget>
<output>12</output>

<result>12</result>