There are 287 pages in a book, and it takes Xiao Ming two weeks to read it. In the first week, Xiao Ming read a total of 140 pages. In the second week, how many pages should he read every day on average?
一本书有287页，小明要用两个星期看完，第一个星期小明共看了140页，第二个星期平均每天要看多少页？
<gadget id="calculator">287 - 140</gadget>
<output>147</output>

<gadget id="calculator">147 / 7</gadget>
<output>21</output>

<result>21</result>