To make the same number of parts, A takes 5 hours and B takes 4 hours, how much higher is the efficiency of A and B than that of A
做同样多的零件，甲用5小时，乙用4小时，甲与乙的效率相比乙的效率比甲高多少
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

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

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

<gadget id="calculator">(1/20) / (1/5)</gadget>
<output>1/4 = around 0.25</output>

<result>1/4 = around 0.25</result>