The school organizes students to visit the patriotic photo exhibition, and hires 2 commentators for every 60 students to make introductions. There are 990 students in the school visiting, how many explainers do we need to hire?
学校组织同学参观爱国主义图片展，每60名同学聘请2名讲解员作介绍．全校990名同学参观，需要聘请几名讲解员？
<gadget id="calculator">60 / 2</gadget>
<output>30</output>

<gadget id="calculator">900 / 30</gadget>
<output>30</output>

<result>30</result>