<PRE><B>Question 254081</B>
Let the speed of car A be x. 
Then,the speed of car B is x-10.
Distance travelled = 560 mile.
Time taken by car A = 560/x
Time taken by car B = 560/(x-10)
Given
         560/x -10 = 560/(x-10)
        (5600-10x)/10x = 560/(x-10)
        (5600-10x)(x-10) = 5600x
        5600x-56000-10x^2+100x = 5600x
        -10x^2+100x-56000 = 0
        x^2-10x+5600 = 0
        (x-80)(x+70) = 0  
                  x  = 80  or -70
 x cannot be negative.
 So, x = 80
Therefore,the speed of car A is 80 miles/h 
and,the speed of car B is x-10 = 80-10 = 70 miles/h</PRE>