There are three boats A, B, and C. Ship A travels 6 kilometers per hour, boat B travels 5 kilometers per hour, and boat C travels 3 kilometers per hour. The three ships set off at the same time, at the same place, and in the same direction, and sailed around the 15-kilometer island. After how many hours, the three ships met again.
有甲、乙、丙三只船，甲船每小时航行6千米，乙船每小时航行5千米，丙船每小时航行3千米．三船同时、同地、同方向出发，环绕周围是15千米的海岛航行，多少小时后，三船再次相会在一起．
<gadget id="calculator">6 - 5</gadget>
<output>1</output>

<gadget id="calculator">15 / 1</gadget>
<output>15</output>

<result>15</result>