There are ten copies of fairy tales. The price of each copy is the same, which is 9.8 yuan Lele wants to buy four sets. Which bookstore is suitable?

There are ten copies of fairy tales. The price of each copy is the same, which is 9.8 yuan Lele wants to buy four sets. Which bookstore is suitable?

Go to a bookstore. Obviously, a bookstore will get one free for three, that is, buy three sets of 3 * 9.8 = 29.4, B bookstore will get 9.8 * 4 * 0.8 = 31.36. Oh, ten books are multiplied by ten, which is the same. When you write, remember to multiply by ten

Xiaogang and Xiaoqiang both want to buy a Book of "100000 whys",
But Xiaogang is short of 4.5 yuan and Xiaoqiang is short of 3.6 yuan. They bought the book together and the rest is 1.8 yuan. How much is the price of a Book of 100000 whys? How many yuan did they take with them?

4.5+3.6=8.1
8.1-1.8=6.3
6.3-4.5=1.8
6.3-3.6=2.7
Xiaogang took 1.8 yuan, Xiaoqiang took 2.7 yuan

A: 80 km / h for trucks. B: 85 km / h for cars, 1980 km apart. They start at the same time and meet each other in? Hours

1980 divided by (80 + 85)=

If the natural numbers a and B satisfy the following conditions: 1 / A + 1 / b = 1 / 3, then how much is a + B?

1/3=4/12=1/12+3/12=1/12+1/4
a+b=12+4=16

Factorization: (A2 + 4) 2-16a2

The original formula = (A2 + 4) 2 - (4a) 2, = (A2 + 4 + 4a) (A2 + 4-4a), = (a + 2) 2 (A-2) 2

Oranges, apples and pears are 1200 kg in total. Oranges weigh three fourths of apples, and apples weigh one fifth less than pears. How many kg do apples weigh

400kg
Let X be apple flavor and y be pear flavor, then we can get x + (3 / 4) x + y = 1200; and X / y = 4 / 5! Finally we can get x + (3 / 4) x + y = 1200
X + (5 / 4) x + (3 / 4) x = 1200! Apple = 400, pear = 500, orange = 300! Understand?

(2Y + 3) of (y + 1) = (6y + 7) of (3Y + 4)

(2y+2+1)/(y+1)=(6y+8-1)/(3y+4)
2+1/(y+1)=2-1/(3y+4)
1/(y+1)=-1/(3y+4)
3y+4=-y-1
4y=-5
y=-5/4
Inspection:

How many kilograms per cubic meter is one gram per cubic centimeter

1 square meter = 1000 square decimeter = 1000000 square centimeter, 1 square meter has 1 ton

The wholesale market of the fruit shop brought in a batch of apples. Two fifths of them were sold in the first day. The next day they sold 6 tons more than the first day. The quality ratio of the apples sold to the rest was 3:7. How many tons more would they sell out the fruits?

The mass ratio of the apples sold to the rest is 3:7, so the fruit sold accounts for 3 / (3 + 7) = 3 / 10 of the total fruit;
On the first day, it sold 2 / 15, and on the second day, it sold 3 / 10-2 / 15 = 5 / 30 = 1 / 6;
The second day sold 1 / 6-2 / 15 more than the first day = 1 / 30;
The next day sold 6 tons more than the first day;
So the total fruit is 6 divided by 1 / 30 = 180 tons;
The remaining Apple 180 * (1-3 / 10) = 126;

How about half by two thirds by 101 by 100?
Simple calculation

1/2x2/3x3x4x…… x100/101=1/101