20、Person A and Person B start from points $A$ and $B$ respectively at the same time, heading towards each other. After they meet, A increases his speed by 10 kilometers per hour, and B decreases his speed by 5 kilometers per hour. When A reaches point B, B is exactly at the midpoint of points $A$ and $B$. If B's original speed was $\frac{2}{2}$ of A's speed, then A's original speed was $\qquad$ kilometers per hour.
【Analysis】When the two people meet, the distance ratio is $3: 2$, which means person A walks 3 parts of the distance, and person B walks 2 parts of the distance.
When person B reaches the midpoint, person B has walked an additional 0.5 part of the distance, and at this point, person A has just arrived at point B, having walked another 2 parts of the distance. Therefore, the speed ratio of the two people is $V_{\text {A }}^{\dot{L}} V=2: 0.5=4: 1$.
Let the original speed of A be $x$, then the original speed of B is $\frac{2}{3} x$.
Then $(x+10):\left(\frac{2}{3} x-5\right)=4: 1 \Rightarrow x=18$