In order to implement small-class education, Zhuyuan Primary School added 5 classes last year, and the number of students in each class of the whole school decreased by 5. This year, another 5 classes were added, and the average number of students in each class of the whole school was reduced by 4. If the total number of students in the school in the past two years No change, how many students are there in total this year?
竹园小学为实行小班化教育，去年增加了5个班级，而全校每班人数减少5人，今年又增加了5个班级，全校每班平均人数又减少4人，如果这两年全校总人数不变，今年共有多少名学生？
<gadget id="calculator">4 * 5</gadget>
<output>20</output>

<gadget id="calculator">20 + 20</gadget>
<output>40</output>

<gadget id="calculator">40 + 5</gadget>
<output>45</output>

<gadget id="calculator">40 * 45</gadget>
<output>1_800</output>

<result>1_800</result>