Print a manuscript, A takes 15 minutes, B takes 18 minutes, how much faster is A than B
打印一份稿件，甲要15分钟，乙要18分钟，甲的速度比乙快多少
<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">1 / 18</gadget>
<output>1/18 = around 0.055556</output>

<gadget id="calculator">(1/15) - (1/18)</gadget>
<output>1/90 = around 0.011111</output>

<gadget id="calculator">(1/90) / (1/18)</gadget>
<output>1/5 = around 0.2</output>

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