If one piece of work can be completed in 4 hours (1/5), then how much of this work can be completed per hour on average.
一件工作，如果4小时可以完成它的(1/5)，那么平均每小时能完成这件工作的多少．
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(1/5) / 4</gadget>
<output>1/20 = around 0.05</output>

<result>1/20 = around 0.05</result>