Lao Wang rides a bicycle from City A to City B to do business. He rides 15 kilometers per hour. When he comes back, he rides a motorcycle and rides 40 kilometers per hour. It takes 2 hours less to ride a motorcycle than to ride a bicycle. How many kilometers away.
老王从甲城骑自行车到乙城去办事，每小时骑15千米，回来时改骑摩托车，每小时骑40千米，骑摩托车比骑自行车少用2小时，甲、乙两城间的距离多少千米．
<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">1 / 40</gadget>
<output>1/40 = around 0.025</output>

<gadget id="calculator">(1/15) - (1/40)</gadget>
<output>1/24 = around 0.041667</output>

<gadget id="calculator">2 / (1/24)</gadget>
<output>48</output>

<result>48</result>