The speed of Altair is 26 km/s, and the speed of Vega is (7/13) of Altair. How many kilometers per second does Vega run slower than Altair?
牛郎星运行速度是26千米/秒，织女星运行速度是牛郎星的(7/13)．织女星每秒运行比牛郎星慢多少千米？
<gadget id="calculator">7 / 13</gadget>
<output>7/13 = around 0.538462</output>

<gadget id="calculator">1 - (7/13)</gadget>
<output>6/13 = around 0.461538</output>

<gadget id="calculator">26 * (6/13)</gadget>
<output>12</output>

<result>12</result>