A 240-page book, after reading it for a few days, the remaining pages are 20 pages less than (2/3) of this book, how many pages are left unread?
一本240页的书，看了几天后，剩下的页数比这本书的(2/3)少20页，还剩下多少页没看？
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">240 * (2/3)</gadget>
<output>160</output>

<gadget id="calculator">160 - 20</gadget>
<output>140</output>

<result>140</result>