The Hope Primary School Painting Interest Group has two classes, A and B. In a painting competition, 18 students from Class A won prizes, and 25% of students from Class B won prizes. The ratio of the number of winners between Classes A and B is 9:5. How many people are there in Class B?
希望小学绘画兴趣小组有甲乙两个班，在一次绘画比赛中，甲班有18人获奖，乙班有25%学生获奖，甲乙两班获奖人数比是9：5，乙班有多少人？
<gadget id="calculator">9 / 5</gadget>
<output>9/5 = around 1.8</output>

<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">18 / (9/5) / (1/4)</gadget>
<output>40</output>

<result>40</result>