20 points are given for five minutes of answering, and 15 minutes plus five 20 minutes equals severa

1. Calculation. Eighths 4 = 1 2 Three-fourths Two-ninths = 1 21 121 Five-elevens = 55 1 Two-thirds = 3 2

Sevenths 7= 1 49 Twenty-fifths 100 = 16 One-half minus one-third = 1 6

7/12 18/35 = 3 10 2/3 4/9 = 8 27 12 3/4 = 9

20 Four-ninths = 45 two-thirds Seven-eighths = 7 12 One-half One-third = 3 2

2. Find the ratio.

24:18=4 3 1/3: 3/5=5 9 : 1/2: 4= 1 8

Three-fifths: one hundred and twenty-seven = 20 9 25m: one-half km = 1 20

3. Simplify the integer ratio.

Half: 9 out of 10 = 5 9 1: 1/2: 7 out of 10 = 5 7 100: 20 = 5

5 Half: 15 = 1 30

4. Calculate the following questions (processes).

Seven out of two, one in seven, minus one in five, one third = 13 30

Three-quarters + three-sevenths minus one-half) Twenty-eight = 20

51 Eight-fifths minus eight-twenty-fifths = 16

8/3 4/9 minus 7/6 minus 5/6 = 4

5. Solve equations.

x three-quarters = eight-thirteenths x=3 26 four-thirds x minus five-sixths x=1 x=11 8

One-third x minus five-sixteenth fifteenth-eighths = two-thirds x=5 2

1 minus a fifth) x = 2 x = 5 2

Are you an elementary school student?

One hour equals 60 minutes, and 15 minutes plus five 20 minutes equals 115 minutes, which is a difference of five minutes, two hours.

:x+y-5=0

x-y-3=0

x=4,y=1.Intersection coordinates: (4,1). Parallel to the straight line 2x+y-3=0,k=-1 2, the linear equation: y=-(1 2)x+b, substituting the intersection coordinates: (4,1) to find the value of b.

b=3 The equation for a straight line is: y=-(1 2)x+3

First, find the intersection point is (4,1), the slope of the parallel line is -2, so the final straight line is 2(x-4)+(y-1)=0, and finally simplify it.

From i1: y=5-x, from i2: y=x-3, the value of y at the intersection is equal, so there is 5-x=x-3, we get x=4, so y=1

Rewrite the straight line 2x+y-3=0, write y=3-2x, and get the slope is -2, so the equation is (y-1)=-2*(x-4), and get 2x+y-9=0, which is the equation of the straight line.

Find the intersection (4, 1) first

The slope of the straight line 2x+y-3=0 is -2

The straight line is y-1 = -2(x-4), i.e. y = -2x + 9

Find the intersection of (1) and (2) first, and get (x1,y1) as (4,1) from x+y-5=0 x-y-3=0

From the slope of 2x+y-3=0 to -2 over (4,1) parallel to 2x+y-3=0 then the slope k=-2 let the equation of the straight line be y=-2x+b and (4,1) into b=9 then y=-2x+9 2x+y-9=0

The second day sold 1 6 on the first day, so the second day sold 2 9 1 6 1 27 thanks fruit. So in two days, a total of 2 9 + 1 27 7 27 were sold

It is flammable, reducing, oxidizing, does not react with water and lime water, and is toxic because it will combine with hemoglobin, and is used as a fuel to smelt metals.

CO2 is non-flammable, only oxidizing, reacts with water and lime water to produce carbonic acid and calcium carbonate, non-toxic, used to extinguish fires, gas fertilizers and so on.

2.The reason for the difference is that the molecular structure is different.

co2+h2o=h2co3

co2+ca（oh）2=caco3↓+h2o

CO is flammable, oxidizing and reducing, does not react with water and lime water, is toxic, and is used to smelt metals.

CO2 is non-flammable, only oxidizing, reacts with water and lime water, is non-toxic, and is used to extinguish fires.

The reason for the difference is that the molecular structure is different.

CO carbon monoxide is flammable. There is reductivity. Does not react with water. Does not react with lime water. Poisonous. Uses: Synthetic methanol.

CO2 carbon dioxide. Non-reducible. Oxidizing. It can be soluble in water to produce carbonic acid. It can be combined with lime water to form a precipitate. Poisonous. It is used to make dry ice.

8x-16=2x+14

Subtract 2x from both sides, 6x-16 = 14

Add 16 on both sides, 6x = 30

Divide by 6 on both sides, x = 5

Multiply the circumference by 8 times 2 by 4 plus multiply 8 by 2 plus it!

A quarter of the area of a large circle minus a small circle.