In 1998, the speed of the train was increased by 30% for the first time, in 1999 for the second time by 25%, and in 2000 for the third time by 20%. How many hours does it take to run.
1998年火车第一次提速30%，1999年第二次提速25%，2000年第三次提速20%，经过这三次提速后，从北京到G城的特快列车只需运行10小时，提速前则需要运行多少小时．
<gadget id="calculator">30 / 100</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">1 + (3/10)</gadget>
<output>13/10 = around 1.3</output>

<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 + (1/4)</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 + (1/5)</gadget>
<output>6/5 = around 1.2</output>

<gadget id="calculator">(13/10) * (5/4) * (6/5)</gadget>
<output>39/20 = around 1.95</output>

<gadget id="calculator">(39/20) * 10</gadget>
<output>39/2 = around 19.5</output>

<result>39/2 = around 19.5</result>