Xiao Ming reads an 80-page story book. He reads the whole book (1/5) on the first day and the whole book (5/16) on the second day. How many pages are left?
小明看一本80页的故事书，第一天看了全书的(1/5)，第二天看了全书的(5/16)，还剩多少页没有看？
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">5 / 16</gadget>
<output>5/16 = around 0.3125</output>

<gadget id="calculator">1 - (1/5) - (5/16)</gadget>
<output>39/80 = around 0.4875</output>

<gadget id="calculator">80 * (39/80)</gadget>
<output>39</output>

<result>39</result>