Sakuyalove has a large world map $M$ and a small world map $m$. Both of the them are in the shape of rectangle. The small map $m$ is compressed from the large map $M$. If the length of $M$ is $a$ and the width of $M$ is $b$, then the length of $m$ is $ka$ and the width of $m$ is $kb$, where $0 < k < 1$. Now Sakuyalove puts the small map $m$ on the large map $M$ such that the small map is completely within the big map (including boundaries). She was surprised to find out that no matter how she places the small map, there always exists
exactly one point $P$ represents the same place in small map and large map (For example, in the following pictures, the location of the pin on both maps represents Tokyo, Japan). Sakuyalove wants to find out this point $P$. Please help her.