Xiao Ming read (1/5) of a book on the first day, the rest (1/2) on the second day, and how much of the whole book on the second day
小明第一天读了一本书的(1/5)，第二天读了余下的(1/2)，第二天读了全书的多少
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(4/5) * (1/2)</gadget>
<output>2/5 = around 0.4</output>

<result>2/5 = around 0.4</result>