When Xiao Ming reads a book, he reads 20 pages on the first day, accounting for 20% of the whole book. After reading it on the second day, the rest (2/5) of the whole book is left. How many pages did he read on the second day?
小明看一本书，第一天看20页，占全书的20%，第二天读后剩下全书的(2/5)，第二天读了多少页？
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

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

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

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

<gadget id="calculator">100 - 20 - 40</gadget>
<output>40</output>

<result>40</result>