The problem of integral Simplification and calculation: 3（a+b-c)+8(a-b-c)-7(a+b-c)-4(a-b-c)

The problem of integral Simplification and calculation: 3（a+b-c)+8(a-b-c)-7(a+b-c)-4(a-b-c)

3（a+b-c)+8(a-b-c)-7(a+b-c)-4(a-b-c)
=3a+3b-3c+8a-8b-8c-7a-7b+7c-4a+4b+4c
=-8b

A passenger train is 200 meters long and a freight train is 280 meters long. They run in opposite directions on parallel tracks. After 18 seconds, when the speed ratio of the passenger train to the freight train is 5:3, the freight train runs every hour______ Kilometers

Suppose that the speed of a freight car is x meters per second and that of a passenger car is 53x meters per second. From the meaning of the question, we get (x + 53x) × 18 = 200 + 280, and the solution is x = 10. That is, the speed of a freight car per hour is 10 × 3600 △ 1000 = 36 (km). So the answer is: 36

A math problem, before nine o'clock, if good high reward
Basketball is an American game.A man(.)James Naismith made it up in1891,He wanted a game to play in winter.The first real game was p(.)in1892.
Naismith put up two peach baskets,There were nine plays on e(.) side.The players tried to l(.)the ball into the baskets,There were no h(.)into the baskets.
When a ball went in the bottom.of the baskets,it s(.) there.The game had to s(.)
A player climbed up to get the ball.It was a slow game.After a w(.)people used net
baskets.They cut the bottom o(.)of the baskets.
At first,many person could play.Now o(.)ten team members play the game.There are five players on each side.Basketball t(.)is a very fast game.

Basketball is an american game.A man ( named) james naismith made it up in 1891.the first real game was p(layed) in 1892.Naismith put up two fruit baskets.there were nine players on ( each ) side.the ...

A math problem. Chase 30!
The volume of a rectangle is 84 cubic centimeters. The sum of the four side areas is 98 square centimeters, and the sum of the top and bottom areas is 24 square centimeters?
Don't use 3 yuan. I can't understand it. By the way, I'm going to sleep at 9:30. That's the question. Kneel down!

What is the area of each bottom
24 △ 2 = 12 square centimeters
What is the height of a cuboid
84 △ 12 = 7 cm
What is the perimeter of the bottom surface
98 △ 7 = 14 cm
The sum of length and width is
14 △ 2 = 7 cm
What is the sum of the lengths of all the edges of this cuboid
(7 + 7) × 4 = 56 cm