After meeting, the speed ratio of AB is 8X:(7X+ 15), and the distance ratio of AB is 7:8. Because they arrived at the same time, therefore:
8X/(7X+ 15)=7/8。 7(7X+ 15)=8*8X, 15X= 105,X=7
Then the speed of the car is a = 8x = 7x8 = 56km/h. ..