Xiaoli s family raised a three tank goldfish, and the water was changed as follows in the evening

1) A: The tap water contains too much fluoride, and the tap water is toxic because it needs to be disinfected and other reasons; B: The best water for feeding fish, there are various microorganisms, after volatilization and precipitation, toxic substances have basically disappeared; C: There is nothing in the water, which is not conducive to the basic survival of the fish.

2) It should also meet the same external environment such as water storage, temperature, and light in the fish tank, because these are the basic conditions for fish survival.

A, fresh tap water is disinfected by the water plant, and it contains more chlorine and is poisoned.

B, after two days of storage in the tank, the chlorine is basically volatilized under open conditions, which is harmless.

C. Boiling water will remove the air from the water, causing severe hypoxia.

If it is a control test, except for the difference in water quality, other conditions should be guaranteed to be exactly the same.

There is not enough oxygen in fresh tap water, boiling water kills the microorganisms in the water, the fish has no food microorganisms that can obtain nutrients, and the water that has been left for two days has enough oxygen and microorganisms in the water, so the fish can live.

There should be as many fish in the tank.

The weather was too hot, and the water temperature was too high, and the fish were gone, and the fish in tank B were strong and died on the third day.

A: Fresh tap water contains chloride that is harmful to goldfish;

B: After two days of storage, the tap water will not cause harm to the goldfish because the chloride in it has volatilized;

C: Boiled cold boiled water, which has insufficient oxygen to provide goldfish with breathing.

Conditions: The size of the goldfish is close or the same, the size of the tank is the same, the number of goldfish in each tank is the same, and the water consumption is the same.

Reason: There can only be one control group, 1-2 experimental groups, and only one condition is different between each experimental group and the control group.

Solution: If the original goldfish x in tank B is set, then the original goldfish in tank A is 3 5x.

x-6=3/5x+6

x-3/5x=6+6

2/5x=12

x=12÷2/5

x=303/5x=3/5*30=18

Answer: There were 18 goldfish in tank A and 30 goldfish in tank B.

Summary. x 24, then the original cylinder B has 24 days, and cylinder A has 42 pieces.

7.There are a total of 66 goldfish in the two tanks of A and B, and if 6 more are put into the first tank, the number of goldfish in the first tank is at this time.

Dear, is it convenient to post the original question?

I reviewed the question, and there are still a few conditions missing.

Pro, the original 42 pieces of cylinder A and 24 pieces of cylinder B.

I don't want answers, I want processes.

I know the answer.

Good. Let's say there are x fish in tank B.

What does the step 66 + 6 = 72 2 + 1 = 3 mean?

2x-6)+x＝66

How can there be an X in elementary school questions?

x 24, then the original cylinder B has 24 days, and cylinder A has 42 pieces.

Dear, we can do it without x.

66+6 equals 72, which means that there is a total total of Uncle Yu.

2+1 3 means that tank A is regarded as 2 fish tanks, and there are 3 fish tanks in total.

72 3 is equal to 24, which is the number of fish in the B fish tank.

Got it. 66-24 42 is the number of people in the turtle tank.

12 (1-60%- 1 4 ) 12 15% =80 (tail pretending to be Qi) Answer: A and B have 80 goldfish in the total bridge of the two fish sensitive tanks

2 A = 1 B.

4C = 1A.

8C = 1B.

1C = 8C-35

8C-35=1C.

35 = 7 C.

C = 55 + 35 = 40 (strips).

Adopt the best! Thank you.

B = 2 A.

A = 4 C. C = B - 35

B = 40 you replace A, B, C with x, y, z This is the ternary equation.

Cylinder B is 8 times that of cylinder C, so cylinder B = 8 * 35 (8-1) = 40 pieces.

Equation: If there are x fish in tank C, then tank B is 8x, tank A is 4x, 8x-x=35, x=5, and tank B is 5x=40.

Draw a line segment diagram, C cylinder is one part, then A cylinder is 4 parts, then B cylinder is 8 parts, C cylinder B cylinder difference 35, it is also 7 parts, one part is 5 (35 divided by 7) B cylinder 8 parts, 5 times 8 equals 40.

It is also possible to solve it with equations.

@设丙缸为x, the first cylinder is 4x, and the second cylinder is 8x, 8x-x=35, x=5, 5x8=40

Solution: A-1=B+1

B-1=(A+1) 50%.

The solution is A = 7 B = 5

Answer: There were originally 7 goldfish in tank A and 5 goldfish in tank B.

A-1 = B+1

A = B + 2 The conclusion is that cylinder A has two more bars than cylinder B.

If you take out 1 piece from cylinder B and put it into cylinder A.

Then cylinder A = 1, B - 1

So at this time, there are four more fish in tank A than in tank B.

If it is an arithmetic, it is 1+1+1+1=4

then 4 for A and 2 for B.

Solution: It turns out that there are x fish in tank A and x-2 fish in tank B.

x-1=x+1

x+1=2(x-1)

x=3B: 3-1=2 (strips).

Answer: Tanks A and B originally had goldfish sticks each.

Let A have x bars and B have 9 7x bars.

9/7x-3=x+3

x=21 is 21 for A, 21 for B, 21 * 9 7 = 27.