Wang Ping plans to read a novel. He reads an average of 28 pages per day in the first 4 days, and 21 pages per day in the next 3 days. How many pages does Wang Ping read on average per day?
王平计划看一本小说，他前4天平均每天看28页，后3天平均每天看21页，求王平平均每天看多少页书？
<gadget id="calculator">28 * 4</gadget>
<output>112</output>

<gadget id="calculator">21 * 3</gadget>
<output>63</output>

<gadget id="calculator">112 + 63</gadget>
<output>175</output>

<gadget id="calculator">4 + 3</gadget>
<output>7</output>

<gadget id="calculator">175 / 7</gadget>
<output>25</output>

<result>25</result>