In an addition problem, if you mistake "8" in the tens place of one addend as "3", and mistake "3" in the units place of the other addend as "8", the resulting sum is 53.71, which is correct And should be how much.
一道加法题，如果把一个加数十分位上的"8"错看成"3"，把另一个加数个位上的"3"错看成"8"，结果和是53.71，正确的和应是多少．
<gadget id="calculator">8 - 3</gadget>
<output>5</output>

<gadget id="calculator">53.71 - 5</gadget>
<output>48.71</output>

<gadget id="calculator">0.8 - 0.3</gadget>
<output>0.5</output>

<gadget id="calculator">48.71 + 0.5</gadget>
<output>49.21</output>

<result>49.21</result>