\(a,\Rightarrow x=\dfrac{7}{3}+\dfrac{6}{7}=\dfrac{49+18}{21}=\dfrac{67}{21}\\ b,\Rightarrow x=\dfrac{15}{7}-\dfrac{13}{14}=\dfrac{30-13}{14}=\dfrac{17}{14}\\ c,\Rightarrow3x=\dfrac{9}{4}-\dfrac{5}{6}=\dfrac{27-10}{12}=\dfrac{17}{12}\\ \Rightarrow x=\dfrac{17}{12}\cdot\dfrac{1}{3}=\dfrac{17}{36}\)

\(x=\dfrac{7}{3}+\dfrac{6}{7}=\dfrac{67}{21}\)

\(x=\dfrac{15}{7}-\dfrac{13}{14}=\dfrac{17}{14}\)

\(x=\left(\dfrac{9}{4}-\dfrac{5}{6}\right):3=\dfrac{17}{36}\)

\(x-\dfrac{6}{7}=\dfrac{7}{3}\\ \Rightarrow x=\dfrac{7}{3}+\dfrac{6}{7}\\ \Rightarrow x=\dfrac{67}{21}\)

\(x+\dfrac{13}{14}=\dfrac{15}{7}\\ \Rightarrow x=\dfrac{15}{7}-\dfrac{13}{14}\\ \Rightarrow x=\dfrac{17}{14}\)

\(\dfrac{9}{4}-3\times x=\dfrac{5}{6}\\ \Rightarrow3\times x=\dfrac{9}{4}-\dfrac{5}{6}\\ \Rightarrow3\times x=\dfrac{17}{12}\\ \Rightarrow x=\dfrac{17}{12}:3\\ \Rightarrow x=\dfrac{17}{36}\)

Bài 1: 

Ta có: \(x-35\%\cdot x=\dfrac{1}{25}\)

\(\Leftrightarrow65\%\cdot x=\dfrac{1}{25}\)

\(\Leftrightarrow x=\dfrac{1}{25}:\dfrac{13}{20}=\dfrac{1}{25}\cdot\dfrac{20}{13}=\dfrac{4}{65}\)

Vậy: \(x=\dfrac{4}{65}\)

Bài 2: 

a) Ta có: \(17\dfrac{2}{31}-\left(\dfrac{15}{17}+6\dfrac{2}{31}\right)\)

\(=17\dfrac{2}{31}-\dfrac{15}{17}-6\dfrac{2}{31}\)

\(=11+\dfrac{2}{31}-\dfrac{15}{17}\)

\(=\dfrac{5366}{527}\)

a) Dấu hiệu là điểm bài thi học kì của 100 học sinh lớp 7 của một trường Trung học Cơ Sở Hòa Bình. Số các dấu hiệu là 100
b) Bảng tần số
 

Nhận xét: Giá trị lớn nhất là 19, giá trị nhỏ nhất là 1; tần số lớn nhất là 13, tần số nhỏ nhất là 1.

Bạn ơi bạn làm đc bao nhiêu thì làm phụ mình nhé 

bài1

a, 

5 - 7 + 3 +(-8)

= -2 + 3 + ( - 8)

=     1    + (-8)= -7

a; - (-5) - (+7) + (+3) + (-8)

  = 5 - 7 + 3  - 8

= (5 + 3 - 8) - 7

= (8 - 8) - 7

= 0 - 7

= - 7

hộ mik nha

a)\(2.x-\frac{3}{2}=\frac{1}{2}\)

\(2x=\frac{4}{2}\)

\(x=\frac{4}{2}:2\)

\(x=1\)

Vậy x=1

b)\(\frac{8}{13}.x+\frac{5}{13}.x=\frac{1}{10}\)

\(x.\left(\frac{8}{13}+\frac{5}{13}\right)=\frac{1}{10}\)\

\(x.1=\frac{1}{10}\)

\(x=\frac{1}{10}\)

Vậy x=\(\frac{1}{10}\)

c)\(\frac{2}{15}+\frac{7}{15}.x=\frac{1}{15}\)

\(\frac{7}{15}x=\frac{-1}{15}\)

x=\(\frac{-1}{7}\)

Vậy \(x=\frac{-1}{7}\)

\(\frac{3}{2}\cdot x-\frac{3}{2}=\frac{1}{2}\)                           \(\frac{8}{13}\cdot x+\frac{5}{13}\cdot x=\frac{1}{10}\)

\(\frac{3}{2}\cdot x=\frac{3}{2}+\frac{1}{2}=2\)                    \(\left[\frac{8}{13}+\frac{5}{13}\right]\cdot x=\frac{1}{10}\)

\(x=2:\frac{3}{2}\)                                            \(1\cdot x=\frac{1}{10}\)

x=\(\frac{4}{3}\)                                                     \(x=\frac{1}{10}:1\)

Vậy x=\(\frac{4}{3}\)                                               \(x=\frac{1}{10}\)

                                                             Vậy x=\(\frac{1}{10}\)

c,\(\frac{2}{5}+\frac{7}{15}\cdot x=\frac{1}{15}\)

\(\frac{7}{15}\cdot x=\frac{1}{15}-\frac{2}{5}=\frac{-1}{3}\)

\(x=\frac{-1}{3}:\frac{7}{15}\)

\(x=\frac{-5}{7}\)

Vậy x=\(\frac{-5}{7}\)

a: =-5/9-4/9+8/15+7/15-2/11=-2/11

b: =10/17+7/17-5/13-8/13+11/25

=11/25

c: =(9/12-2/12)*3/2=7/12*3/2=21/24=7/8

d: =(31/10-25/10)*3-2

=3/5*3-2

=9/5-2

=-1/5

1. -x+20 = -(-15)-8+13

=> -x=15-8+13-20

=> -x=0

=> x=0

2. -(-10)+x=-13+(-9)+(-6)

=> 10+x=-13-9-6

=> x = -13-9-6-10

=> x = -38

3. 8-(-12)+10=-(-14)-x

=> 8+12+10=14-x

=> x = 14-8-12-10

=> x = -16

4. -(+12)+(-x)-(-3)=5-(-7)

=> -12-x+3=5+7

=> -x=5+7+12-3

=> -x=21

=> x=-21

5. 14-x+(-10)=-(-9)+(+15)

=> 14-x-10=9+15

=> -x=9+15-14+10

=> -x=20

=> x=-20

6. 12-(-17)+(-3)=-5+x

=> 12+17-3+5=x

=> x=31

7. x-(-19)-(+32)=14-(+16)

=> x+19-32=14-16

=> x=14-16+32-19

=> x=11

8. x-|-15|-|7|=-(-9)+|-5|

=> x-15-7=9+5

=> x=9+5+7+15

=> x=36

9. 15-x+17=13-(-21)

=> 15-x+17=13+21

=> -x=13+21-15-17

=> -x=2

=> x=-2

10. -|-5|-(-x)+4=3-(-25)

=> -5+x+4=3+25

=> x=3+25-4+5

=> x=29

...=-15-9=-24

...=4+7=11

...=-12-13=-25

...=13+10=23

...=-4-7=-11

...=-9+13=4

...=12+0=12

...=0-7=-7

...=0+3=3

...=15-17=-2

...=-6

...=-23

...=15-15=0

-15-(+9) = -24

4-(-7) = 11

-12+(-13) = -25

-(-13)-(-10) = 23

-4-(+7) = -11

(-9)-(-13) = 4

-(-12)+0 = 12

0-(+7) = -7

0-(-3) = 3

15-17 = -2

-18+12 = -6

-5-18 = -23

-(-15)+(-15) = 0

-24

11

-25

23

-11

4

12

-7

3

-2

-6

-23

0

\(105-\left[\left(2x+7\right)-13\right]=\left(-15\right)^{10}:\left(9^5.5^8\right)\\ 105-\left[\left(2x+7\right)-13\right]=25\\ \left(2x+7\right)-13=105-25\\ \left(2x+7\right)-13=80\\ 2x+7=80+13\\ 2x+7=93\\ 2x=93-7\\ 2x=86\\ x=\dfrac{86}{2}\\ x=43\)

\(105-\left[\left(2x+7\right)-13\right]=\left(-15\right)^{10}:\left(9^5.5^8\right)\\ 105-\left[\left(2x+7\right)-13\right]=15^{10}:3^{10}:5^8\\ 105-\left[\left(2x+7\right)-13\right]=5^{10}:5^8\\ 105-\left[\left(2x+7\right)-13\right]=25\\ \left(2x+7\right)-13=105-25\\ \left(2x+7\right)-13=80\\ 2x+7=80+13\\ 2x+7=93\\ 2x=93-7\\ 2x=86\\ x=86:2\\ x=43\)