Xiaohong regards the plus sign as a minus sign when calculating 309+128, so the calculated result is much more than the correct result
小红计算309+128时把加号看成了减号，这样算出的结果比正确的结果多少
<gadget id="calculator">309 + 128</gadget>
<output>437</output>

<gadget id="calculator">309 - 128</gadget>
<output>181</output>

<gadget id="calculator">437 - 181</gadget>
<output>256</output>

<result>256</result>