The minuend remains unchanged, but the subtrahend decreases by 100, what is the difference?
被减数不变，减数减少100，差多少．
<gadget id="calculator">200 - 100</gadget>
<output>100</output>

<gadget id="calculator">200 - 0 - 100</gadget>
<output>100</output>

<result>100</result>