Two ships, A and B, set off from two ports that are 418 kilometers apart at the same time. Ship A sails 36 kilometers per hour, and ship B sails 34 kilometers per hour. One hour after departure, Ship A has an urgent mission. Return to the original port, and immediately set sail to meet the second ship. How many hours have passed before the two ships meet?
甲乙两艘轮船，由相距418千米的两个港口同时相对开出，甲船每小时航行36千米，乙船每小时航行34千米，开出1小时后，甲船因有紧急任务，返回原来港口，又立即起航与乙船相对开出，经过多少小时两船相遇？
<gadget id="calculator">34 * 2</gadget>
<output>68</output>

<gadget id="calculator">418 - 68</gadget>
<output>350</output>

<gadget id="calculator">36 + 34</gadget>
<output>70</output>

<gadget id="calculator">350 / 70</gadget>
<output>5</output>

<gadget id="calculator">1 * 2</gadget>
<output>2</output>

<gadget id="calculator">5 + 2</gadget>
<output>7</output>

<result>7</result>