The front tires of the bicycle are scrapped after driving 9000 kilometers, and the rear tires are scrapped after driving 7000 kilometers. The front and rear tires can be exchanged at the right time. How many kilometers can a bicycle run with a pair of new tires at the same time?
自行车的前轮轮胎行驶9000千米后报废，后轮轮胎行驶7000千米后报废，前后轮胎可在适合时候交换位置．问一辆自行车同时换上一对新轮胎最多可行驶多少千米？
<gadget id="calculator">16 / 63_000</gadget>
<output>2/7_875 = around 0.000254</output>

<gadget id="calculator">2 / (2/7_875)</gadget>
<output>7_875</output>

<result>7_875</result>