Teacher Sun bought 5 packs of notebooks for 135 yuan, each pack of 9 notebooks, how much is each notebook?
孙老师用135元买来5包笔记本，每包9本，每本笔记本多少元？
<gadget id="calculator">5 * 9</gadget>
<output>45</output>

<gadget id="calculator">135 / 45</gadget>
<output>3</output>

<result>3</result>