The waterway from Nanjing to Wuhan is about 840 kilometers long. Two ships depart from opposite places at the same time, the ship from Wuhan travels 26 kilometers per hour, and the ship from Nanjing travels 16 kilometers per hour. After how many hours did the two ships meet on the way?
南京到武汉的航道长大约840千米．两艘轮船同时从两地相对开出，武汉开出的轮船每小时行26千米，南京开出的轮船每小时行16千米．经过多少小时两艘轮船在途中相遇？
<gadget id="calculator">26 + 16</gadget>
<output>42</output>

<gadget id="calculator">840 / 42</gadget>
<output>20</output>

<result>20</result>