A book has 257 pages in total. Xiao Ming read 43 pages yesterday and 57 pages today. How many pages are left?
一本书共257页，小明昨天看了43页，今天又看了57页，还剩多少页没看？
<gadget id="calculator">43 + 57</gadget>
<output>100</output>

<gadget id="calculator">257 - 100</gadget>
<output>157</output>

<result>157</result>