Math 3 Urgent, thank you

1.If there is a slope road x km and a flat road k y km, then the camp will be from the camp to the school (x+y) km.

x/12 + y/9 = 11/12

x/6 + y/9 = 7/6

solution, we get x = 3, y = 6

So x + y = 9

A: The school is 9 km from the camp.

2.Let the speed of A be x km/h and the speed of B ykm/h.

y）= 28

2x + 2（x + y）= 28

solution, we get x = 6, y = 2

Answer: A's speed is 6 km/h.

3.If the hundred digits are A, the ten digits are B, and the single digit is C, then the ten digits are 100A+10B+C

b = a + c

b - c = 2

100c -10b -a）-（100a + 10b + c）-= 99

solution, we get a = 2, b = 5, c = 3

A: This three-digit number is 253

It took 15 minutes (1 4 hours) to go to and from back, that is, the time difference between going up and down the mountain, and if the uphill distance is x, then x 12 + 1 4 = x 6, and x=3 km is obtained, so from the summer camp to the school, the uphill time is 15 minutes, the flat road is 40 minutes, and the total distance is 3 + 9 * (2 3) = 9 km.

A and B set off from two places 28 kilometers apart at the same time and met 3 hours and 30 minutes later. If A sets off 2 hours first, then B meets A 2 hours after departure, and finds A's speed.

The distance they walked together in two hours is 28*(2 km, then A walked 28-16=12 km) alone, and his speed is 6 km/h.

Let the ten-digit tail x, then the single digit is x-2, and the number on the hundred digit is 2, then there is an equation 200 + 10 * x + x-2 + 99 = 100 * x - 200 + 10 * x + 2, the solution gets x = 5, and the three-digit number is 253, in fact, you already know that the hundred digit is 2, and the new one is 99 larger than the original, that is, the difference between the single digit and the hundred digit is a 9, 2 + 10-9 = 3 (on the single digit) so that you get 253.

1. As fast, set the leveling speed to x. then the uphill speed is and the downhill speed is 2x.

The time taken for flat ground is 1 x

The time taken to break the road is (1 3) Cong Kaitong.

So both roads are just as fast.

2. The unit price after mixing is (2A+4B) (A+B), which is unreasonable. When Sun Xi a=b, the unit price is three, if it is not equal, it is unreasonable.

x+35)=15%

4. (15%*30) 30+x)=(18%*20) (20+x) The solution is x=20

and 24, the greatest common factor is 12

Therefore, the length of the sides of the largest square that can be cut is 12, and the number of squares is 36 24 12 12 = 6.

and the least common multiple of 60 is 180

Distance from A to B = 45 (21-1) = 900 m 900 180-1 = 5-1 = 4

So in addition to the one at the beginning that does not need to be moved, there are four in the middle that do not have to move the least common multiple 72

72 72 (72 18) = 4 blocks.

The greatest common factor is 12, so 36 12 * (24 12) = 6 (pcs).

2) There are 20 gaps in 21 roots, and every 45 meters, there are 20 * 45 = 900 (meters) in 900 is a multiple of 45 and 60: 180, 360, 720, 900 So in addition to the first one is not moving, there are 4 roots that are not moving.

3) The least common multiple of 72 and 18 is 72, so the minimum 72 72 * (72 18) = 4 (block) is required

2. 2a（ab+ac-b^2-bc）=02a[a(b+c)-b(b+c)]=0

2a(b+c)(a-b)=0 Because a, b, and c are all positive numbers, b+c is greater than 0, and a is greater than 0, so a-b is equal to 0, that is, a=b.

3.The original formula can be seen as the square difference of two numbers, so it can be reduced to (10 12+25+10 12-25) (10 12+25-10 12+25)=2*10 12*50=10 14

So n=14

S1+S3=S2 S1=BC 2 S3=Ca 2 S2=Ab 2 According to the Pythagorean theorem Bc 2+Ca 2=Ab 2 The same is true of the relationship between the right semicircles, and according to the Pythagorean relation of the side length of the triangle, the calculated relationship between the three small semicircles is S2+S3=S1.

Set the time it takes for Tom to complete the t

9(1/45+1/30+1/x)=1

The three of them shared 9 hours.

1 of the total amount of work done per person per hour (each completed independently).

1) Boys: Average: (132+156+161+145+159+147) 6=150 Median: (145+147) 2=146

Girls: Average: (138+147+136+157+150+160) 6=148 Median: (147+150) 2=

2) Average: (132 + 156 + 161 + 145 + 159 + 147 + 138 + 147 + 136 + 157 + 150 + 160) 12 = 149

Median: 132 136 138 145 147 147 150 156 157 159 160 161