It takes 2 hours for a car to go from A to B, and 2.5 hours to return. How much faster is the speed when going than when returning.
一辆汽车从甲地开往乙地去时用了2小时，返回时用了2.5小时，去时比返回时的速度快多少．
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 / 2.5</gadget>
<output>0.4</output>

<gadget id="calculator">(1/2) - 0.4</gadget>
<output>0.1</output>

<gadget id="calculator">0.1 / 0.4</gadget>
<output>0.25</output>

<result>0.25</result>