Xiao Ming walked from home to school. It took him 10 minutes to go and 8 minutes to return. How much faster was the speed when he returned than when he went.
小明从家走到学校，去时用了10分钟，回时用了8分钟，回时的速度比去时提高了多少．
<gadget id="calculator">1 / 8</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">(1/8) - (1/10)</gadget>
<output>1/40 = around 0.025</output>

<gadget id="calculator">(1/40) / (1/8)</gadget>
<output>1/5 = around 0.2</output>

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