Unit mid-term and end-of-term special sprint 100, answer to P85-88 in the first volume of sixth grade mathematics in primary school!
Set the speed of vehicle A to 5 km/h and the speed of vehicle B to 7 km/h..
(5x+7x)*4=600*80%
x= 10
The speed of vehicle A is10 * 5 = 50km/h.
The speed of car B is10 * 7 = 70 km/h.