A and B leave from both places at the same time. A travels 45 kilometers per hour, while B drives 8 / 9 of the speed per hour. After four hours, the two cars go to the same place How far is the distance between a and B

A and B leave from both places at the same time. A travels 45 kilometers per hour, while B drives 8 / 9 of the speed per hour. After four hours, the two cars go to the same place How far is the distance between a and B

B speed 45x8 / 9 = 40
(45 + 40) X4 △ 1-20% = 340 △ 0.8 = 425km
A: the distance between a and B is 425 km

A section of highway is 240 km long. Two vehicles run from two places at the same time. After two hours of meeting, it is known that the speed ratio of vehicle a and vehicle B is three to one. How many kilometers does vehicle a travel per hour?

A per hour
240÷2÷（3+1）x3
=120÷4x3
=90 km

When a and B are driving on a straight road, the passengers in car a see that car B is moving southward. When the passengers in car B see that car a and trees are moving southward, the following statement is correct
A. Both cars may move southward
B. Both cars may go north
C. Car a moves northward, car B moves southward
D. Car a must move to the South and car B to the north
Let's talk about the principle

Because the trees can't move, car a and the trees move southward, which means car B must move northward. Car a may not move, or it may not move as fast northward as car a