Renmin Primary School donated 200 books and 30 pencil cases to the primary school in the mountainous area. It cost 1200 yuan in total. Each pencil box was 12 yuan. How much is the average book?
人民小学向山区小学捐赠了200本图书和30个文具盒，一共花了1200元，文具盒每个12元，平均每本图书多少元？
<gadget id="calculator">30 * 12</gadget>
<output>360</output>

<gadget id="calculator">1_200 - 360</gadget>
<output>840</output>

<gadget id="calculator">840 / 200</gadget>
<output>21/5 = around 4.2</output>

<result>21/5 = around 4.2</result>