car travels from place A to place B. It takes 4 hours to go, and it takes 1 hour to return. How much faster is the speed when returning than when going.
一汽车从甲地到乙地，去时用了4小时，返回时比去时快1小时，返回时的速度比去时的速度快多少．
<gadget id="calculator">4 - 1</gadget>
<output>3</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(1/3) - (1/4)</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">(1/12) / (1/4)</gadget>
<output>1/3 = around 0.333333</output>

<result>1/3 = around 0.333333</result>