car drives from place A to place B at 20 kilometers per hour. When the halfway point is 25 kilometers, increase the speed to 50 kilometers per hour. The average speed of this trip is 25 kilometers per hour. How many kilometers is the whole journey between places A and B?
一辆车从甲地开往乙地，每小时行20千米，当行到全程的一半多25千米时，把速度提高到每小时50千米．这样行完全程的平均速度是每小时25千米．甲乙两地全程多少千米．
<gadget id="calculator">5 * 1</gadget>
<output>5</output>

<gadget id="calculator">5 + 1</gadget>
<output>6</output>

<gadget id="calculator">25 * 6</gadget>
<output>150</output>

<result>150</result>