The whole journey takes 1 as the unit and is divided into six sections on average. Li Wei walked three paragraphs, Zhao Gang walked four paragraphs, Zheng Ming walked six paragraphs, *** 13 paragraphs, each 3 yuan, so Li You 9 yuan, Zhao Gang 12 yuan, Zheng Ming 18 yuan.

Calculation:

1÷( 1+ 1/2+2/3)= 13/6

Li Wei: 39÷ 13/6 × 1/2 =9 (yuan)

Zhao Gang: 39÷ 13/6 ×2/3 = 12 (yuan)

Zheng Ming: 39 ÷13/6×1=18 (yuan)