There are five story books and six science and technology books. The total price is 135 yuan. It is known that the price of two story books and three science and technology books is equal. How much is each story book and one science and technology book?

Story book 15 yuan a Book
Science and technology book 10 yuan a Book

It costs 156 yuan to buy three sci-tech books and six story books; it costs 150 yuan to buy six sci-tech books and three story books. How much are the sci-tech books and story books?
Please do it by removing

Science and technology book (150 × 2-156) / (6 × 2-3)
=144÷9
=16 yuan
Storybook (156-16 × 3) △ 6
=108×6
=18 yuan

Given y = 13x-1, then the value of 13x2-2xy + 3y2-2 is______ ．

∵y=13x-1，∴13x2-2xy+3y2-2=13（x2-6xy+9y2）-2=13（x-3y）2-2=13×9-2=1．

The beverage store stipulates that coke is 6 yuan for "buy ten get one free". How much does Xiao Wang have to pay for 43 bottles of coke

(30+9)*6=234

The negative x power of 2 multiplied by the negative x power of 5 = 0.1 (x-1 power of 10) to the fifth power

The result is x = 1,

A passenger car is going from place a to place B, and a freight car is going from place B to place a. the train runs through the midpoint of 28km and meets the passenger car. The relationship between the passenger car and the freight car is known
The speed ratio is 5:7. How many kilometers does the truck have to travel to reach Jiadi after meeting?

It is known that the speed ratio of passenger cars to freight cars is 5:7
Because the time is equal, so the speed ratio = distance ratio = 5:7
28 × 2 ÷ (7-5) × (7 + 5) = 336km (whole journey)
After the meeting, the truck will travel 336 × 5 / 12 = 140 km to Jiadi
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1 / 2004 + 2 / 2004 + 3 / 2004 ····· + 100 / 2004 simple calculation, formula idea!

1/2004+2/2004+3/2004······+100/2004
=1/2004×（1+2+3+…… +100）
=1/2400×5050
=101/48

A and B leave from two places at the same time. A travels 80 kilometers per hour. B's speed is 7 / 8 of a's. after three hours, the two cars are thousands of miles away
A and B leave from two places at the same time. Car a travels 80 kilometers per hour. Car B's speed is 7 / 8 of car a's. after three hours, the two cars are still 10% of the whole distance. How many kilometers are there between the two places

The speed of B car: 80 × 7 / 8 = 70 km / h
In three hours, the two trains were running: (80 + 70) × 3 = 450 km
Distance between the two places: 450 ÷ (1-10%) = 500 km
You can ask me if you don't understand

Equation 4-6x-6.5 of 0.01 = 0.02-2x-7 of 0.02
(1) X = - 1 / 8 (2) x = 1 / 2 (3) x = 4 / 5 (4) x = - 3 / 8

(4-6x)/0.01-6.5=(0.02-2x)/0.02)-7.5
400-600x=1-100x-1
500x=400
x=4/5
Choose C

The distance between a and B is 600km. The two vehicles start from the two places at the same time, and they meet at 3 hours. It is known that the speed of a and B is 11:9,
What are the speeds of car a and car B?

600 △ 3 = 200 km / h
200 ÷ (11 + 9) × 11 = 110 km / h The speed of car a
200 ÷ (11 + 9) × 9 = 90 km / h Speed of car B

There are five story books and six science and technology books. The total price is 135 yuan. It is known that the price of two story books and three science and technology books is equal. How much is each story book and one science and technology book?