The distance between A and B cities is 420 kilometers. There is a tower between A and B cities. The ratio of the distance between the tower and A and B cities is 5:2. How many kilometers is the tower from B city?
甲乙两城相距420千米，在甲乙两城之间有一座塔，塔距甲乙两城市的距离比是5：2，塔距乙城有多少千米？
<gadget id="calculator">5 + 2</gadget>
<output>7</output>

<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">420 * (2/7)</gadget>
<output>120</output>

<result>120</result>