Obviously doing a subtraction problem, I copied the subtraction wrong. The subtraction should be 24, but he copied it into 42, and the calculated difference is 30. Do the math, what is the correct difference for this question?
明明做一道减法题，把减数抄错了．减数应该是24，他都抄成了42，算出的差是30，你算算，这道题正确的差是多少？
<gadget id="calculator">30 + 42</gadget>
<output>72</output>

<gadget id="calculator">72 - 24</gadget>
<output>48</output>

<result>48</result>