Sijichun shoe store has 60 pairs of shoes on 3 shelves. If there are 180 pairs of shoes, how many shelves are needed?
四季春鞋店，用3个货架摆了60双鞋，如果有180双鞋，那么需要多少个货架．
<gadget id="calculator">60 / 3</gadget>
<output>20</output>

<gadget id="calculator">180 / 20</gadget>
<output>9</output>

<result>9</result>