It used to take 20 minutes for Xiao Ming to go from home to school, but today it took 25 minutes. Today's speed is much slower than before.
小明从家到学校，原来要用20分钟，今天用了25分钟，今天的速度比原来降低了多少．
<gadget id="calculator">1 / 20</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">1 / 25</gadget>
<output>1/25 = around 0.04</output>

<gadget id="calculator">(1/20) - (1/25)</gadget>
<output>1/100 = around 0.01</output>

<gadget id="calculator">(1/100) / (1/20)</gadget>
<output>1/5 = around 0.2</output>

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