Because the little sloppy miscalculated 20*(□+2) into 20*□+2, how much difference is the result he got from the correct result
由于小马虎把20*(□+2)错算成了20*□+2他得到的结果与正确的结果相差多少
<gadget id="calculator">20 * 2</gadget>
<output>40</output>

<gadget id="calculator">40 - 2</gadget>
<output>38</output>

<result>38</result>