A passenger car and a truck drive in opposite directions from the middle of A and B at the same time for 3 hours. The bus arrives at A and the truck is 42 kilometers away from B. The speed ratio of the truck and the bus is 5:7. How many kilometers are there between A and B?
客车和货车同时从甲、乙两地的中间向相反方向行驶3小时后，客车到达甲地，货车离乙地还有42千米，已知货车和客车的速度比是5：7．甲、乙两地相距多少千米？
<gadget id="calculator">5 / 7</gadget>
<output>5/7 = around 0.714286</output>

<gadget id="calculator">1 - (5/7)</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">42 / (2/7)</gadget>
<output>147</output>

<gadget id="calculator">147 * 2</gadget>
<output>294</output>

<result>294</result>