Because they are required to meet at point A, they both run integer circles. The distance of each lap is the same, so the running distance is directly proportional to the number of laps.

Because they set out at the same time and met at point A, they ran for the same time, so the distance and speed were directly proportional.

So the number of laps two people run is directly proportional to the speed.

The speed ratio of A and B is 5:7, so the ratio of laps is also 5:7. Because the number of laps is an integer, the minimum number of laps is 5 and 7 respectively.

They ran 7+5= 12 laps.

They met once when they ran a lap, so they met 12 times. If we count the time together, we met 13 times.