A book, Xiao Ming read the whole book (1/3) in the first week, read 40% of the whole book in the second week, and left 120% unread. How many pages are there in total?
一本书，小明第一个星期看了全书的(1/3)，第二个星期看了全书的40%，还剩120没有看．全书一共有多少页？
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (1/3) - (2/5)</gadget>
<output>4/15 = around 0.266667</output>

<gadget id="calculator">120 / (4/15)</gadget>
<output>450</output>

<result>450</result>