A Ford car left A to B and an Audi car left B to A at the same time. The speed of the Ford car to that of the Audi car was 4:3. The Ford decreased its speed by 25% and the Audi car increased its speed by 25% after they had passed each other. When the Ford car reached B, the Audi car was still 20 km away from A. Find the distance between A and B in km.