Two equation questions, two questions, equation solution

A can complete 1 12 of the total dam repair project every day, and B can complete it in four days if A completes it in three days, so B completes (1 12) * (3 4) = 1 16 of the total project every day.

Two days later, B repaired all 2*(1 16)=1 8;

Set A to catch up with B after x days; Then:

x/12=x/16+1/8；

Solution: x=6 (days).

There are a total of x people;

then: k·x +2 = 7x-14;

7-k）x = 16；

x and k are both positive integers, then: only.

x=16，k=6；Or.

x=8，k=5；Or.

x=4，k=3

That is: 16 people, 8 or 4 people in total.

v A = 1 12

v B = 3 4v A = 1 16

1 16) 2+x 16=x 12 gives x=67x-14=kx+2

x=16/(7-k)

k = 3 x = 4

k = 5 x = 8

k = 6 x = 16

1.From the question, it can be seen that B can complete 1 16 of the total works every day.

It takes x days. then there is (2+x) 16=x 12

The solution is x=6

2.Let the number of people be A and the number of books be B.

Then the question: {ak=b-2

a-2)*7=b

Eliminate b then there is 7a-14=ak-2, and the shift terms are combined to get (7-k)*a=16, so 1=my level can only be reduced to this, so try them one by one after that, no trouble.

1.Half an hour sedan car: 9 15 = , 9 + 1 + 20 = 30 minutes of fierce bells.

2.Let the distance closure line s original velocity be v

s v=4 hours, (s+10) (v+2)=, the result v=8 s=32 km.

1. Solution: It took Xiao Ming a total of x minutes to arrive at the school.

x-1=（1-9/15）*50+9

x=20+9+1

x = 30 minutes.

A: Xiao Gangyi shared 30 minutes to get to school.

2. Let the person's original speed be x kilometers per hour.

4x+10=(4+

4x+10=

x = 8 kmh.

The distance between A and B is 4*8=32 kilometers.

(1) Solution: obtained by 2: 4x - 6y - 4= 0 by - obtained: 6y + 9y - 5= 0

15y = 5

y = 1 / 3

Substituting y = 1 3 yields: 2x - 1 = 0x = 1 2

Obtained by 2: x - 2y = 6

From -, 3y = -3

y = -1

Substituting y = -1 yields: x + 2 = 6x = 4

x = 4

y = -1

{2x+3y-2=0 ①

4x-9y+1=0 ②

Solution: 3+ got.

10x-5=0

Solution: x=1 2

Substituting x=1 2 into the equation yields:

y=1/3x=1/2

y=1 3 is obtained by substituting Eq. 1 by x=5y+9 by substituting Eq. 2.

3(2(5y+9)-5)-4(3y+4)=3(10y+13)-4(3y+4)=18y+23=5

So y=-1

So x=4

1. Multiply the equation by 3 and add it to the equation to get x=, and then substitute it to calculate the value of y;

2. The equation obtains x=5y 9, substitutes the equation, solves y=1, and then substitutes to solve the value of x.

2x＋3y—2=0 ①

4x—9y＋1=0 ②

1 type *2-2 type.

15y-5=0

y=1 3 substitute y=1 3 into 1.

2x+3*1/3-2=0

2x-1=0

x=1/2x＋1=5（y＋2）..1

3（2x—5）—4（3y＋4）=5...2

Obtained by 1 formula. x-5y=9...3 is obtained by 2.

x-2y=6...Type 44-Type 3.

3y=-3y=-1

Substituting y=-1 into equation 4 yields.

x-2*(-1)=6

x+2=6x=4

Five solutions: set apples per kilogram of x yuan.

124x+100×1=

124x x six solutions: set pants x yuan, tops 62 + x

62+x=2x-10

x=62+10

x =7262+x =134

The top is 134 yuan, and the pants are 72 yuan.

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Sixth, the unit price of pants is yuan, then the unit price of the jacket is 2 -10, according to the title: 2 -10 - = 32

3. Let x minutes meet for the first time, 350x+250x=400, and solve x=2 3 minutes = 40 seconds; After 2*40=80 seconds for the second encounter.

4. Let the distance be x km, x 15 + 24 60 = x 12-15 60, and the solution is x = 39 km.