A. The distance between B and a is 150 kilometers. The speed of car a is 55 kilometers per hour, and that of car B is 45 kilometers per hour. If two cars go in the same direction from a and B (car a is behind car B), how long does it take for car a to catch up with car B? Let X

A. The distance between B and a is 150 kilometers. The speed of car a is 55 kilometers per hour, and that of car B is 45 kilometers per hour. If two cars go in the same direction from a and B (car a is behind car B), how long does it take for car a to catch up with car B? Let X

Starling, you can ask me directly-
Let's catch up in X hours
55x-45x=150
10x=150
x=15
A: catch up in 15 minutes
Myna ~ your class papers, generally our class have done=
What else, help me add reward points ~ I'm greedy~
Also, it should be right, but SA, don't blame me for doing it~

It is known that the speed of passenger cars is 70 km / h and that of freight cars is 55 km / h. on a straight road, two cars travel from a and B places 400 km apart at the same time
How many kilometers is the distance between the two cars after 2 hours

In the same direction:
(1) The direction of passenger car is toward freight car, 55 * 2 + 400-70 * 2 = 370
(2) 70 * 2 + 400-55 * 2 = 430
Reverse:
(1) Opposite, 400 - (70 + 50) * 2 = 160
(2) Reverse, 400 + (70 + 50) * 2 = 640

The distance between a and B is 310 km. A and B drive from both places at the same time. A runs at 55 km / h and B runs at 65 km / h
How long does it take to continue driving after meeting? The distance between the two vehicles is 74 km?

(310 + 74) / (55 + 65) = 3.2 hours

equation
When a car is driving at a constant speed on the road, it sees a two digit milestone. One hour later, it sees a two digit milestone, and its ten digit milestone is reversed from the first two digit milestone. Another hour later, it sees a three digit milestone, It's the first time to see a "0" in the middle of the two digits, to find the speed of the car and the number on the first milestone?

The first tens of digits must be 1. Let its one digit be X,
So the two digits you see for the first time are 10 + X
The second two digits you see are 10x + 1
The third number you see is 100 + X
The car has a uniform speed
10x＋1－（10＋x）＝100＋x－（10x＋1）
10x＋1－10－x＝100＋x－10x－1
9x－9＝99－9x
18x＝108
x＝6
The number of cars seen for the first time was 16, the number of cars seen for the second time was 61, and the number of cars seen for the third time was 106
The speed of the car is 61-16 = 45 km / h