Li Fei bought a pen and 4 notebooks for a total of 27 yuan, and a pen for 15 yuan. How much is each notebook?
李飞买了一枝钢笔和4本笔记本一共花了27元，一枝钢笔15元，每本笔记本多少元？
<gadget id="calculator">27 - 15</gadget>
<output>12</output>

<gadget id="calculator">12 / 4</gadget>
<output>3</output>

<result>3</result>