Xiaohong calculated 7*(△+4) into 7*△+4, how much is her answer different from the correct answer?
小红将7*(△+4)计算成了7*△+4，她的答案与正确答案相差多少．
<gadget id="calculator">7 * 4</gadget>
<output>28</output>

<gadget id="calculator">28 - 4</gadget>
<output>24</output>

<result>24</result>