When Xh was established, it was used to take a flat road, and when yh came back, it was used to take a flat road.

5x+3*(6-x)=2*y+4*(8-y) (equal round-trip distance)

5x=2y (equal roads)

x= 2 y= 5

Flat road 5x= 10

Slope road 3*(6-x)= 12