Three, A and B start from locations $A, B$ respectively, heading towards each other. They meet at point $C$ on the way, after which A takes 5 hours to reach $B$, and B takes $3 \frac{1}{5}$ hours to reach $A$; it is known that A walks 1 kilometer less per hour than B. Find the distance between $A$ and $B$.
Three, Hint: Let $A C=S_{1}, C B=S_{2}$, the time required for both to meet is /small hour, then we get $t=4$ hours. From the problem, we solve to get $S_{1}=16, S_{2}=20$. Therefore, $A B=35$ km.