An express train and a slow train travel towards each other from places A and B at the same time, and after 3 hours of driving, the distance is still 210 kilometers. It is known that the express train takes 8 hours to complete the journey, and the speed ratio of the express train and the slow train is 3:2. How many kilometers is the distance between A and B?
一列快车和一列慢车，从甲乙两地同时相向而行，开出3小时后还相距210千米．已知快车行完全程要8小时，快车与慢车的速度比3：2，甲乙两地相距多少千米？
<gadget id="calculator">1 / 8</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">(1/8) * (2/3)</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">(1/8) + (1/12)</gadget>
<output>5/24 = around 0.208333</output>

<gadget id="calculator">3 * (5/24)</gadget>
<output>5/8 = around 0.625</output>

<gadget id="calculator">1 - (5/8)</gadget>
<output>3/8 = around 0.375</output>

<gadget id="calculator">210 / (3/8)</gadget>
<output>560</output>

<result>560</result>