57 * 2 =114km

3*2

Suppose two people are at the same speed.

Then the midpoint is the meeting point ... the speed should be different, and the distance from the midpoint is 3km, so 3*2 means that A walks more than B.

So, 3*2/(20- 18)

In addition to the extra distance per hour, the time when they met was also counted.

Multiply the meeting time by 18, which is the distance B walked. This distance plus 3 is half of the total distance, and then multiplied by 2 is the total distance.

Primary schools can write this question step by step.