If x + 7 / a = 6, then the value of 7x + A is? A.1 B.7 C.6 D.42

If x + 7 / a = 6, then the value of 7x + A is? A.1 B.7 C.6 D.42

42. Multiply the left and right sides of the previous formula by 7 to get the answer Hehe

How to solve 10x = 7x + 3.7 × 6

10x=7x+3.7x6
3x=22.2
x=7.4

Train a and B set out from a and B 480 km apart at the same time and run in opposite directions. Train a runs 50 km per hour and train B 70 km per hour
How many hours later did the two cars meet?

Let's meet in X hours
50x+70x=480
120x=480
x=4

（2X-3）+（X-3）=36

（2X-3）+（X-3）=36
3x-6=36
3x=6+36
3x=42
x=14

After eight hours of meeting each other, it is known that the speed ratio of the two vehicles is 4:3, and the speed ratio of the two vehicles is 4:3

A is 40 km / h, B is 30 km / h

A decimal move his decimal point to the right one place, 2.88 larger than the original number, to find the original decimal!
Quick answer, a lot of points! Quick

It is the problem of difference times: the smaller number = difference / (multiple-1) the difference between two numbers is 2.88, the number after the decimal point is moved one place to the right is 10 times larger than the original number, 2.88 △ (10-1) = 0.32 (original number)

Three hours later, the passenger and freight cars run in the opposite direction from the middle of a and B at the same time. The bus is 42 kilometers away from B, and the speed ratio of goods and passengers is 5 to 7
How many meters is the distance between a and B
There is a mistake in the question, the truck is 42 kilometers away from B

I think it's a truck
In proportion
5：7=（X/2-42）：X/2
X=298

Real number reduction:
(1) 7 radical 3-radical 1 / 3
(2) Root 40-5 root 1 / 10 + root 10
(3) (radical 20 + radical / radical 5) - 2
(4) Root 12 + root 27 / root 3
(5) (radical 3 + radical 2) × (radical 3-radical 2)
(6) Radical 1 / 7 + radical 28 - radical 700
(7) Root 32-3 root 1 / 2 + root 2

(1) 7 radical 3-radical (1 / 3)
=7 radical 3 - radical 3 / 3
=21 radical 3 / 3 - radical 3 / 3
=20 root 3 / 3
(2) Root 40-5 root 1 / 10 + root 10
=2 radical 10 - 1 / 2 radical 10 + radical 10
=5 root 10 / 2
(3) (radical 20 + radical / radical 5) - 2 wrong questions
(4) Root 12 + root 27 / root 3
= 2 radical 3 + 3 radical 3 / radical 3
= 2 radical 3 + 3
(5) (radical 3 + radical 2) × (radical 3-radical 2)
= square of root 3 - square of root 2
＝1
(6) Radical 1 / 7 + radical 28 - radical 700
= radical 7 / 7 + 2 radical 7-10 radical 7
= - 55 radical 7 / 7
(7) Root 32-3 root 1 / 2 + root 2
= 4 radical 2 - 3 / 2 radical 2 + radical 2
= 9 / 2 radical 2

For a and B trains, the speed of a train is 54 kilometers per hour, and that of B train is 10 meters per second
The wrong time of driving is more than 40 seconds. If car a is 100 meters long, how long is car B
If two vehicles travel in the same direction, the passing time is 40 seconds longer than that in the same direction

Suppose that it takes T1 seconds for two vehicles to travel in the same direction, T2 seconds for two vehicles to travel in the opposite direction, and the length of vehicle B is x meters
（15-10）* t1=100+x
（15+10）* t2=100+x
t1-t2=40
The final solution is x = 150
Vehicle B is 150 meters long

The average of the three numbers is 50, and the ratio of the three numbers is 3:7:5. What are they?

The total is 50 * 3 = 150
150*3/（3+7+5）＝30
150*7/（3+7+5）＝70
150-30-70＝50