SOLUTION: Two persons travel by car to separate cities in the same amount of time. The first person travels 310 km sat an average speed that is three kms per hour faster than the second pers

Let x be the average speed of the slower car, in kilometers per hour.


Then the faster car's average speed is (x+3) km/h.


The "time" equation is


     = .      { " in the same amount of time " )


Solve it for x.


For it, cross multiply to get


    310*x = 215*(x+3)

    310x = 215x + 645

    310x - 215x = 645

    95x = 645

    x =  = 6.8 kilometers per hour (approximately).


Very strange answer, for the car' speed - but such are the input data in your post.