Xiaodong is reading a 300-page book. He reads 25 pages a day. After reading for 3 days, how many pages are left?
小东在看一本300页的书，他每天看25页，看了3天后，还剩多少页没看．
<gadget id="calculator">25 * 3</gadget>
<output>75</output>

<gadget id="calculator">300 - 75</gadget>
<output>225</output>

<result>225</result>