In a certain class, the average score of the mathematics test was 84.2. Later, it was found that Xiaohong's score was 96, which was mistakenly counted as 69. After recalculation, the average score was 84.7. How many students are there in this class?
某班统计数学考试成绩，平均成绩是84.2分，后来发现小红的成绩是96分，而被错误地统计为69分，重新计算后，平均成绩是84.7分，这个班有多少名学生？
<gadget id="calculator">96 - 69</gadget>
<output>27</output>

<gadget id="calculator">84.7 - 84.2</gadget>
<output>0.5</output>

<gadget id="calculator">27 / 0.5</gadget>
<output>54</output>

<result>54</result>