Yucai Primary School built a new 3-story teaching building with 6 classrooms on each floor. We bought 720 sets of desks and chairs for these classrooms. How many sets of desks and chairs are placed in each classroom on average? (by comprehensive formula)
育才小学新建一幢3层的教学楼，每层有6间教室，买来720套课桌椅放在这些教室里，平均每间教室放多少套课桌椅？(用综合算式)
<gadget id="calculator">6 * 3</gadget>
<output>18</output>

<gadget id="calculator">720 / 18</gadget>
<output>40</output>

<result>40</result>