It used to take 6 hours for a train to go from station A to station B, but now it only takes 4 hours. How much is the speed increased?
一列火车原来从甲站到乙站要6小时，后来只需要4小时，提速了百分之几？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">(1/4) - (1/6)</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">(1/12) / (1/6)</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">100 / 100</gadget>
<output>1</output>

<gadget id="calculator">(1/2) * 1</gadget>
<output>1/2 = around 0.5</output>

<result>1/2 = around 0.5</result>