In a Chinese language test in a class, one student missed the test due to illness. The average score based on the actual number of students was 89.8. Later, this student scored 100 points in the make-up test. At this time, the average score of the whole class was 90 points. How many students are there in this class?
一个班语文测验，有一名同学因病缺考，按实有人数计算平均分是89.8分，后来这名学生补考得100分，这时全班平均分数是90分，这个班有多少名学生？
<gadget id="calculator">100 - 89.8</gadget>
<output>10.2</output>

<gadget id="calculator">90 - 89.8</gadget>
<output>0.2</output>

<gadget id="calculator">10.2 / 0.2</gadget>
<output>51</output>

<result>51</result>