Proportionally, the distance between Party A and Party B is 5: 3. That is, the ratio of driving distance, the ratio obtained by removing the common factor. Let the common factor be x, then 5X-3X= 12 and X=6, then the distance traveled by B is 3*6= 18km, because A and B spend the same time, so the speed of B is 18/8=2.25.