6. There are two docks, $\mathrm{A}$ and $\mathrm{B}$, on a river, with $\mathrm{A}$ upstream and $\mathrm{B}$ downstream. Two people, Jia and Yi, start from $\mathrm{A}$ and $\mathrm{B}$ respectively at the same time, rowing towards each other, and meet after 4 hours. If Jia and Yi start from $\mathrm{A}$ and $\mathrm{B}$ respectively at the same time, rowing in the same direction, Yi catches up with Jia after 16 hours. It is known that Jia's rowing speed in still water is 6 kilometers per hour, then Yi's rowing speed in still water is $\qquad$ kilometers per hour.
【Key Points】Journey, Boats in Running Water
【Difficulty】※ふう
【Answer】 10
【Analysis】In the problem of boats in running water, the speed sum when two boats meet is the sum of the two boats' speeds, and the speed difference when one boat catches up with the other is the difference of the two boats' speeds.
Let the speed of boat B be $x$ kilometers/hour;
$$
4(6+x)=16(x-6)
$$

Solving for $x$ gives $x=10$