1. A and B vehicles leave from two places 420 kilometers apart at the same time, and meet four hours later. The speed ratio of a and B vehicles is 4:3. What are the speeds of a and B vehicles? 2. There are three groups in class 6 (1) to plant trees. Each group plants trees according to the number of people. How many trees should each group plant? There are 16 people in the first group, 14 people in the second group and 18 people in the third group. There are 72 trees in total

1. A and B vehicles leave from two places 420 kilometers apart at the same time, and meet four hours later. The speed ratio of a and B vehicles is 4:3. What are the speeds of a and B vehicles? 2. There are three groups in class 6 (1) to plant trees. Each group plants trees according to the number of people. How many trees should each group plant? There are 16 people in the first group, 14 people in the second group and 18 people in the third group. There are 72 trees in total

1. If the speed of car a is 4x, then the speed of car B is 3x
(3x+4x)*4=420
7x=105
x=15
The speed of car a is 4x = 60, and that of car B is 3x = 45
2. One group: 72 ÷ (16 + 14 + 18) * 16 = 24
Group 2: 72 ÷ (16 + 14 + 18) * 14 = 21
Three groups: 72 ÷ (16 + 14 + 18) * 18 = 27

The distance between two places is 800 meters. Party A and Party B start from two places at the same time. If they go in opposite directions, they will meet in 4 minutes. If they go in the same direction, they will catch up in 50 minutes

800 ÷ (a + b) = 4 A + B = 200
800 ÷ (a-b) = 50 A-B = 16
A = (200 + 16) △ 2 = 108 (M / min)
B = (200-16) △ 2 = 92 (M / min)

The distance between a and B is 1800. After a and B meet, a arrives at B in 8 minutes, B arrives at a in 18 minutes,
The distance between a and B is 1800. A starts from a and B starts from B. after a and B meet, a arrives at B in 8 minutes and B arrives at a in 18 minutes,

Suppose that the velocity of a is x and that of B is y, and it takes t minutes from starting to meeting, then (x + y) * t = 1800x * t + X * 8 = 1800y * t + y * 18 = 1800y * 18 = t * XX * 8 = t * y, the fourth and fifth equations X / y = 3 / 2x = y * 3 / 2 are substituted into any one of the last two equations to get t = 12 minutes, and the first three equations to get x = 90 / min, y = 60 /

Party A and Party B set out at the same time from two places AB, and they walked towards each other. After meeting, Party A went to place B in 48 minutes, and Party B went to place a in 27 minutes,
What's the speed ratio between a and B?
The answer should be clear, and it's better to solve it within today

Let the distance between a and B be 1 unit, the velocity of a be x unit / min, and the velocity of B be y unit / min
The time taken for Party A and Party B to meet is
1/(x+y)
The time of a from a to B can be expressed as 1 / (x + y) + 48 = 1 / X
The time of B from a to B can be expressed as 1 / (x + y) + 27 = 1 / y
After finishing the equation, we get
(y/x)/(x+y)=48 (1)
(x/y)/(x+y)=27 (2)
(1) (2) get
(y/x)^2=16/9
So y / x = 4 / 3
A: the speed ratio is 3:4