Who will teach me some math problems? 1. Cut the 7 meter long wire into 9 sections, each section is 1 meter long (), the whole length (), and each section is () meters long 2. An iron block with a volume of 12 cubic decimeters sinks into a cuboid container with a length of 8 decimeters and a width of 3 decimeters, and the water surface rises () decimeters A、2 B、1.5 C、1 D、0.5 3. 12 tons of goods are transported by car, 6 / 11 of the goods are transported in three times. How many parts of the goods are transported each time? How many tons are transported each time? 4. A square wood, 7 meters long, cut into 4 sections, the surface area increased by 96 square centimeters, the original volume of square wood is how much? You big brothers and sisters, teach little sister ~ I write big head

1. The 7 meter long wire is cut into 9 sections, each section is 1 meter long (7 / 9), the whole length is 1 / 9, and each section is 7 / 9 meters long
2. If a 12 cubic decimeter iron block sinks into a cuboid container with a length of 8 decimeters and a width of 3 decimeters, the water surface will rise by (d) decimeters
A、2 B、1.5 C、1 D、0.5
3. 12 tons of goods are transported by car, 6 / 11 of the goods are transported in three times. How many parts of the goods are transported each time? How many tons are transported each time?
6 / 3 of 11 = 2 of 11 12 * 2 of 11 = 24 of 11 tons
4. A square wood, 7 meters long, cut into 4 sections, the surface area increased by 96 square centimeters, the original volume of square wood is how much?
(4-1) * 2 = 3 * 2 = 6 96 / 6 = 16 square centimeter, 7m = 700 centimeter, 16 * 700 = 11200 cubic centimeter

① Wang Ming went to see his mother-in-law at the weekend. He bought 15.5kg apples, pears and bananas with 74 yuan in the supermarket. Apples are 2kg more than pears. It is known that apples are 5 yuan per kilogram, pears are 5.51kg and bananas are 4 yuan per kilogram?
② There are three kinds of goods: A, B and C. If you buy 3 pieces of a, 7 pieces of B and 1 piece of C, it costs 315 yuan in total. If you buy 4 pieces of a, 10 pieces of B and 1 piece of C, it costs 420 yuan in total. How much does it cost to buy one piece of a, B and C?

1: Suppose the pear has x kilogram
5（x+2）+5.5x+4（15.5-2x-2）=74
The solution is: x = 4
What grade is the second course?

1. A factory has 226kg raw materials of a and 250kg raw materials of B. it plans to use these two raw materials to produce 40 pieces of a and B products. One kind of a product needs 7kg raw materials of a and 4kg raw materials of B. one kind of B product needs 3kg raw materials of a and 10kg raw materials of B. suppose to produce X pieces of a product, calculate the value of X, and explain which kinds of production plans are in line with the theme. If the raw materials of a and B are 50 yuan / kg and 40 yuan / kg respectively, 2. If a cosmetic shop goes to the manufacturer to buy 5 sets of a and 6 sets of B cosmetics, it will cost 950 yuan; if it buys 3 sets of a cosmetics and 2 sets of B cosmetics, it will cost 450 yuan. How much are the two kinds of a and B cosmetics? If one set of a cosmetics can make a profit of 30 yuan, A set of b-brand cosmetics can make a profit of 20 yuan. And the number of b-brand cosmetics purchased is more than twice that of a-brand cosmetics. In this way, the total profit of cosmetics sold will not be less than 1200 yuan. How to purchase?

Answer to question 1: solution:
Suppose the quantity of product a is x (x is a positive integer), then the quantity of product B is 40-x,
Then according to the total amount of raw materials of a and the consumption relationship of raw materials required by ab products
7x+3(40-x)≤226
We get x ≤ 31.5
According to the total amount of B raw materials and ab products need B raw materials consumption relationship
4x+10(40-x)≤250
We get x ≥ 25
5 and X ≥ 25, and X is a positive integer, x = 25 26 27 29 30 31
The corresponding 40-x has 15 14 13 12 11 10 9
That is to say, there are seven schemes, and the number of AB products is
(25,15) (26,14) (27,13) (28,12), (29,11) (30,10) (31,9)
Because a raw material is 50 yuan / kg, B raw material is 40 yuan / kg, that is, a is greater than B,
If you want to have a better plan, that is to say, the cost is the lowest, that is, you should use as many kinds of raw materials as possible
According to the total amount of B raw materials and the consumption relationship of B raw materials required by ab products, the formula is as follows:
4x+10(40-x)≤250
x≥25
Take x = 25, just will b raw materials all used up, the cost is the lowest, the scheme is better
Answer to the second question: (1) suppose that the purchase price of a brand of cosmetics is x yuan, and that of B brand of cosmetics is y yuan
The results show that 5x + 6y = 9503x + 2Y = 450 and 8203;
The solution is x = 100y = 75 & # 8203
A: the purchase price of a and B brands is 100 yuan and 75 yuan respectively
(2) If M sets of cosmetics of a brand are purchased, then (2m + 4) sets of cosmetics of B brand are purchased
According to the meaning of the title: 2m + 4 ≤ 4030m + 20 (2m + 4) ≥ 1200 &;
The solution is 16 ≤ m ≤ 18
∵ m is a positive integer, ∵ M = 16,17,18 ∵ 2m + 4 = 36,38,40
A: there are three purchase plans
(1) A brand of cosmetics to buy 16 sets, B brand of cosmetics to buy 36 sets
(2) A brand of cosmetics to buy 17 sets, B brand of cosmetics to buy 38 sets
(3) A brand of cosmetics to buy 18 sets, B brand of cosmetics to buy 40 sets

I can't do some math problems, please teach them
One third of a pile of coal and one half of this pile of coal add up to 40 tons. How many tons are there in this pile of coal?
A car from a to B, the first hour driving a quarter of the whole journey, the second hour driving a third of the whole journey, at this time, there are still 100km away from B. how many kilometers between a and B?
It's urgent!

One third of a pile of coal and one half of this pile of coal together is 40 tons. How many tons of coal is there? 40 (1 / 3 + 1 / 2) = 48 tons. There are 48 tons of coal in this pile. A car drives from land a to land B, one fourth of the whole journey in the first hour and one third of the whole journey in the second hour. At this time, it is still 100km away from land B

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