Xiao Ming reads a 200-page book, and reads an average of 25 pages a day in the first 4 days, and finishes the rest within two days. How many pages does he need to read on average every day?
小明看一本200页的书，前4天平均每天看25页，剩下的要在两天内看完，平均每天要看多少页．
<gadget id="calculator">4 * 25</gadget>
<output>100</output>

<gadget id="calculator">200 - 100</gadget>
<output>100</output>

<gadget id="calculator">100 / 2</gadget>
<output>50</output>

<result>50</result>