After a train speeds up, the running time from city A to city B is shortened from 10 hours to 8 hours now. How much does the speed of this train increase?
一列火车提速后，从甲城到乙城的运行时间由原来的10小时缩短到现在的8小时，这列火车的速度提高了多少．
<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) / (1/10)</gadget>
<output>1/4 = around 0.25</output>

<result>1/4 = around 0.25</result>