A and B ride bicycles from city A to city B at the same time. A travels 15 kilometers per hour, and B travels 12 kilometers per hour. A is delayed for 4 hours due to something on the way. As a result, A and B arrive at city B at the same time. Find the distance between cities A and B.
甲、乙两人同时骑自行车从A城到B城，甲每小时行15千米，乙每小时行12千米，甲由于途中有事耽误了4小时，结果甲和乙同时到达B城．求A、B两城间的距离．
<gadget id="calculator">15 - 12</gadget>
<output>3</output>

<gadget id="calculator">4 / 3</gadget>
<output>4/3 = around 1.333333</output>

<gadget id="calculator">15 * (4/3) * 12</gadget>
<output>240</output>

<result>240</result>