Xiao Fang reads a science and technology book. On the first day, he reads 20 pages, accounting for 1/5 of the whole book, and on the second day, he reads 40% of the whole book; how many pages are left?
小方读一本科技书，第一天读了20页，占全书的(1/5)，第二天读了全书的40%；还剩多少页没有看？
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">20 / (1/5)</gadget>
<output>100</output>

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

<gadget id="calculator">1 - (1/5) - (2/5)</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">100 * (2/5)</gadget>
<output>40</output>

<result>40</result>