A river flows through two cities A and B. The speed of a boat sailing downstream on a river is 30 kilometers per hour; the speed of sailing upstream is 22 kilometers per hour. The difference between the time it takes to go from A to B by boat and the time it takes to go from B to A is 4 hours, then , What is the distance in kilometers between cities A and B?
一条河流经过A、B两座城市．一条船在河上顺流航行的速度是每小时30公里；逆流航行的速度是每小时22公里，乘船从A到B花费的时间是与从B到A花费的时间之差为4小时，那么，A、B两座城市之间的距离是多少公里？
<gadget id="calculator">30 * 11</gadget>
<output>330</output>

<result>330</result>