When Xiaohong calculates 20+□*4, she calculates the addition first and then the multiplication. How much is the difference between the result she calculated and the correct result.
小红在计算20+□*4时，先算加法，后算乘法了，她计算得到的结果与正确的结果相差多少．
<gadget id="calculator">80 - 20</gadget>
<output>60</output>

<result>60</result>