Class 51 has a math exercise, and the average score is 89 points. Only Xiao Qiao and Xiao Ding Ding did not participate in the practice due to illness, and their make-up exam scores were 100 and 93 points respectively the next day. If the scores of the two of them are added, the average score of Class 51 this time is 89.5 points. How many students are there in this class.
五1班一次数学练习，平均成绩是89分．只有小巧、小丁丁两人因病没有参加练习，第二天他俩的补考成绩分别是100分和93分．如果加上他俩的成绩后，五1班这次的平均成绩是89.5分．这个班有多少个学生．
<gadget id="calculator">89 * 2</gadget>
<output>178</output>

<gadget id="calculator">93 - 178</gadget>
<output>-85</output>

<gadget id="calculator">100 + (-85)</gadget>
<output>15</output>

<gadget id="calculator">89.5 - 89</gadget>
<output>0.5</output>

<gadget id="calculator">15 / 0.5</gadget>
<output>30</output>

<result>30</result>