Given the equation system ax + by = 15, ① ax by = - 1 / 2, ② because a misread a in ①, the equation system {x = - 3, y = - 1} is obtained; B misread B in ②, the solution of the equation system is {x = 5, y = 4}. If calculated according to the correct a and B, the solution of the original equation system is {x = 5, y = 4}?

Given the equation system ax + by = 15, ① ax by = - 1 / 2, ② because a misread a in ①, the equation system {x = - 3, y = - 1} is obtained; B misread B in ②, the solution of the equation system is {x = 5, y = 4}. If calculated according to the correct a and B, the solution of the original equation system is {x = 5, y = 4}?

A misread a in (1) and did not misread equation (2), so substituting x = - 3 and y = - 1 into equation (2) leads to
-3a+b= -1/2 ,---------------（3）
Similarly, substituting x = 5, y = 4 into (1) yields 5A + 4B = 15, - -------- (4)
A = 1, B = 5 / 2,
So the original equation is x + 5Y / 2 = 15, x-5y / 2 = - 1 / 2,
It is easy to get x = 29 / 4, y = 31 / 10

It is known that the system of equations x + 2Y = 10, ax + by = 1 about X, y has the same solution as the system of equations BX + AX = 6, 2x-y = 5. Find out the section and the value of a, B
Xiao Zhao's family had a balance of 500 yuan last year. It is estimated that this year's balance is 950 yuan. This year's income is 15% higher than that of last year, and the expenditure is 10% lower than that of last year. What's the income and expenditure of last year?
Points sent in the shortest time

1、
It is the same solution of these four equations
So we first solve x + 2Y = 10 (1)
2x-y=5(2)
(1)+(2)×2
5x=20
x=4,y=2x-5=3
Put in the other two
4a+3b=1 (3)
4b+3a=6 (4)
(3)+(4)
7a+7b=7
a+b=1 (5)
(3)-(5)×3
a=-2
b=1-a=3
So the solution is x = 4, y = 3
a=-2,b=3
2、
Suppose last year's income is X Yuan and expenditure is y yuan
Then this year's income (1 + 15%) x = 1.15x, expenditure (1-10%) y = 0.9Y
So last year's balance X-Y = 500 (1)
This year, 1.15x-0.9y = 950 (2)
(2)-(1)×0.9
1.15x-0.9x=950-450
0.25x=500
x=2000
y=x-500=1500
A: last year, the income was 2000 yuan and the expenditure was 1500 yuan

There are 450 chickens and ducks in the feeding group. Half of the chickens are sold and another 30 ducks are bought, which is twice as much as ducks. How many chickens and ducks are there?

Suppose chicken x duck y
X+Y=450
X/2=2(Y+30)
X=384,Y=66
According to the title, the original number of chickens is 4 times of the total number of ducks plus 30 ducks. Therefore, the original number of ducks plus 5 times of the total number of 30 ducks, and the number of ducks equals 450 + 30 = 480. Then the original number of ducks is 66 and the number of chickens is 384

Uncle Zhang raised 200 geese, 60% more ducks than geese. How many ducks did he raise?

200 * (1 + 60%) = 320
320 ducks

Uncle Zhang has two hundred ducks. The number of ducks is three eighths less than that of chickens. How many chickens are there?

That's three eighths of 200. The answer is 320

There are 270 ducks in the farm. (1) the number of chickens is 25% less than that of ducks. How many chickens are there
(2) The number of ducks is 25% more than that of chickens. How many chickens are there?
Formula:
(3) The number of chickens is 25% more than that of ducks. How many chickens are there?
Formula:
(4) The number of ducks is 25% less than that of chickens. How many chickens are there?
Formula:

(1) The number of chickens is 25% less than that of ducks, and the number of chickens is 270x (1-25%) (2) the number of ducks is 25% more than that of chickens, and the number of chickens is 270x (1 + 25%) (3) the number of chickens is 25% more than that of ducks, and the number of chickens is 270x (1 + 25%) (4) the number of ducks is 25% less than that of chickens

How many percent more ducks than chickens?
The number of chickens is 25% of that of ducks. How many percent more ducks than chickens?

Taking the number of ducks as unit 1, the number of chickens is 1 × 25% = 0.25 (1-0.25) △ 0.25 = 300%. The number of ducks is 300% more than that of chickens

The number of chickens in the factory is 25% more than that of ducks. How many percent less are ducks than that of chickens?

Let the number of ducks be 1, then the number of chickens is: 1 × (1 + 25%) = 1.25; (1.25-1) △ 1.25 = 0.25 △ 1.25 = 20%; answer: the number of ducks is 20% less than that of chickens

A batch of feed for 8 ducks and 5 chickens for 10 days, or 12 ducks and 6 chickens for 7 days, for 10 ducks and 15 chickens for () days?

6 days
Let every duck eat feed x every day and every chicken eat feed y every day. The number of days is a
so （8x+5y）*10＝（12x+6y）*7＝（10x+15y）*a
so a＝6
A: this batch of feed can feed 10 ducks and 15 chickens for 6 days

There are 16 chickens and 12 ducks. How many percent more chickens than ducks?

Multiple = (16-12) △ 12 = 1 / 3 ≈ 33.3%