For a book, 40% of the book has been read, and the remaining pages are 60 more than the one that has been read. How many pages have been read?
一本书，已读了全书的40%，剩下的比已读的多60页，已读了多少页．
<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5) - (2/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">60 / (1/5)</gadget>
<output>300</output>

<gadget id="calculator">300 * (2/5)</gadget>
<output>120</output>

<result>120</result>