Read a 450-page book, read the whole book (1/3) on the first day, and read the whole book (2/5) on the second day, how many pages are left?
读一本450页的书，第一天读了全书的(1/3)，第二天读了全书的(2/5)，还剩多少页没读？
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">2 / 5</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">450 * (4/15)</gadget>
<output>120</output>

<result>120</result>