From a to b, go down the mountain first, and then take a flat road. Someone rides a bike from A to B at a speed of 12km/h, but it takes 55 minutes to get to B by crossing a flat road at a speed of 9km, and it takes 1.5h to get the distance between A and B after coming back by crossing a flat road at a speed of 8km and going uphill at a speed of 4km. ..

I don't know if you have studied binary linear equations. If not, solve it with a linear equation of one variable.

Suppose the downhill time is x and the flat slope time is 55/60-x.

Then the distance to the mountain is: 12X, and the distance to the flat is: (1112-x) * 9.

Then according to the regression velocity and time series equation:

(1112-x) * 9/8+12x/4 =1.5

X= 1/4

That is, the distance to the mountain is: 12 * 1/4 = 3km, and the distance to the flat is: (1112-1/4) * 9 = 6km, and Party A and Party B *.