1) Assuming that the train ticket and the boat fare have increased by one fifth on the return trip, the travel fare should be 250*( 1+ 1/5)=300 yuan, but only 280 yuan was spent, and 20 yuan, which spent less, was only because the train fare increased by 10%,/kloc-0.

2)

Because C just ran to the midpoint between A and B, C ran all the way (2/3+3/4)/2 = 17/24,

And it is 350 meters away from the finish line, so the distance from the start point to the finish line is 350/(1-kloc-0/7/24) =1200 meters.

3) It's too difficult to think about not using equations! If the equation is used, assuming that the original planned driving time is t and the original speed is v, there are

(t-2)* 10=2x，

(t+0.5)*2=0.5x，

If the solution is t = 12 and x = 50, the distance between Party A and Party B is t * x = 50 *12 = 600km.

(See which expert has the ability to give a non-equation method)