Two ships A and B are traveling towards each other from two docks at the same time. Ship A travels 40 nautical miles per hour, and ship B travels 28 nautical miles per hour. After traveling for 4 hours, the distance between the two ships is still 30 nautical miles. How many nautical miles are there between A and B?
甲、乙两艘轮船分别从两个码头同时相向而行．甲船每小时行40海里，乙船每小时行28海里，两船行驶4小时后还相距30海里．甲、乙两个码头相距多少海里？
<gadget id="calculator">40 + 28</gadget>
<output>68</output>

<gadget id="calculator">68 * 4</gadget>
<output>272</output>

<gadget id="calculator">272 + 30</gadget>
<output>302</output>

<result>302</result>