Xiaoqiang reads a story book. He reads (3/5) of the whole book on the first day and (1/5) of the whole book on the second day.
小强看一本故事书，第一天看了全书的(3/5)，第二天看了全书的(1/5)，还剩多少没有看．
<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (3/5) - (1/5)</gadget>
<output>1/5 = around 0.2</output>

<result>1/5 = around 0.2</result>