book has 800 pages. Xiao Ming has read (2/5) of the whole book in a week. How many pages are left?
一本书有800页，小明一个星期看了全书的(2/5)，还剩多少页没看？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">800 * (3/5)</gadget>
<output>480</output>

<result>480</result>