On a map with a scale of 1:3,000,000, the distance between A and B is 7 cm. If it is drawn on a map with a scale of 1:5,000,000, how many centimeters is the distance between A and B?
在比例尺是1：3000000的地图上，量得甲、乙两个城市的距离是7厘米，如果画在比例尺是1：5000000的地图上，甲、乙之间的距离是多少厘米？
<gadget id="calculator">1 / 3_000_000</gadget>
<output>1/3_000_000 = around 0</output>

<gadget id="calculator">7 / (1/3_000_000)</gadget>
<output>21_000_000</output>

<gadget id="calculator">1 / 5_000_000</gadget>
<output>1/5_000_000 = around 0</output>

<gadget id="calculator">21_000_000 * (1/5_000_000)</gadget>
<output>21/5 = around 4.2</output>

<result>21/5 = around 4.2</result>