₁₎ ( 2002 - 79 + 15 ) - ( -79 + 15 ) = 2002 

₂₎ - (515 - 80+ 91 ) - ( 2003 + 80 + 91 ) = -2700 

₃₎ 4573 + 46 - 4573 + 35 - 16 - 5 = 60

₄₎ 32 + 34 + 36 + 38 - 10 - 12 - 14 - 16 - 18 = 70 

tách ra đi 

Dài quá :(

dài quá vậy

5x(15x Y)=515:5+2

=>5x(15y)=103+2

=>5x(15y)=105

=>15y=105:5

=>15y=21

=>y=7/5

Ps:lan sau bn dung dang may cau nhu nay nua nhe, mik nghi cam but tu lm se nhanh hon day.

5 nhan ( 15 nhan y)= 515 :5 +22

5 nhân (15 nhân y) = 103 +22= 125

15 nhân y = 125:5 = 25

y = 25:15 = 5 / 3= 1,(6)

\(5\times(15\times y)=515:5+2\)

\(75\times y=103+2\)

\(75\times y=105\)

\(y=\frac{105}{75}=\frac{7}{5}\)

b) Đ

1) 15:(x+2) = 3

x + 2 = 15 : 3

x + 2 = 5

x = 5 - 2

x = 3

2) 20:(1+x) = 2

1 + x = 20 : 2

1 + x = 10

x = 10 - 1

x = 9

3) 5(x+35) = 515

x + 35 = 515 : 5

x + 35 = 103

x = 103 - 35

x = 68

4) 541+(218-x) = 73

218 - x = 73 - 541

218 - x = -468

x = 218 - ( - 468 )

x = 686

5) 1230:3 (x-20) = 10

410 . ( x - 20 ) = 10

x - 20 = 10 : 410

x - 20 = 1/41

x = 1/41 + 20

x = 821/41

6) 48-3(x+5) = 24

3( x + 5 ) = 48 - 24

3( x + 5 ) = 24

x + 5 = 24 : 3

x + 5 = 8

x = 8 - 5

x = 3

7) 4x + 18 : 2=13

4x + 9 = 13

4x = 13 - 9

4x = 4

x = 1

8) X-48:16 = 37

x - 3 = 37

x = 37 + 3

x = 40

a, 15: (x+2) = 3

x+2 =15:3

x+2 = 5

x = 5-2

x = 3

b, 20: (1+x) = 2

1+x = 20:2

1+x = 10

x = 10-1

x = 9

c, 5(x+35) = 515

x+35 = 515 :5

x+35 = 103

x = 103-35

x = 68

d, 541+ (218-x) = 73

218-x = 73-541

218-x = - 468

x = 218 - (-468)

x = 218 + 468

x = 686

e, 1230:3. (x-20) = 10

410(x-20) = 10

x-20 = 10: 410

x-20 = 1/41

x = 1/41 + 20

x = 821/41

f, 48-3(x+5) = 24

3(x+5) = 48-24

3(x+5) = 24

x+5 = 24:3

x +5 = 8

x = 8-5

x =3

g, 4x + 18 : 2 = 13

4x + 9 = 13

4x = 13-9

4x = 4

x = 4:4

x = 1

j, x - 48:16 = 37

x- 3 = 37

x = 37+3

x = 40

1: =-12

2: =11

Bài 1: Tính

a) Ta có: \(\left(-25\right)\cdot68+\left(-34\right)\cdot\left(-250\right)\)

\(=-25\cdot68+\left(-340\right)\cdot\left(-25\right)\)

\(=-25\cdot\left(68-340\right)\)

\(=-25\cdot\left(-272\right)\)

\(=6800\)

b) Ta có: \(1999+\left(-2000\right)+2001+\left(-2002\right)\)

\(=1999-2000+2001-2002\)

\(=-1-1=-2\)

c) Ta có: \(515+\left[72+\left(-515\right)+\left(-32\right)\right]\)

\(=515+72-515-32\)

\(=40\)

d) Ta có: \(\left(2736-75\right)-2736+175\)

\(=2736-75-2736+175\)

\(=100\)

e) Ta có: \(-2020-\left(157-2020\right)-\left(-257\right)\)

\(=-2020-157+2020+257\)

\(=100\)

Bài 2: Tìm x

a) Ta có: \(x-\left|-2\right|=\left|-18\right|\)

\(\Leftrightarrow x-2=18\)

hay x=20

Vậy: x=20

b) Ta có: \(2x-\left|+14\right|=\left|-14\right|\)

\(\Leftrightarrow2x-14=14\)

\(\Leftrightarrow2x=28\)

hay x=14

Vậy: x=14

c) Ta có: \(\left|x+4\right|+5=20-\left(-12-7\right)\)

\(\Leftrightarrow\left|x+4\right|+5=20+12+7\)

\(\Leftrightarrow\left|x+4\right|=39-5=34\)

\(\Leftrightarrow\left[{}\begin{matrix}x+4=34\\x+4=-34\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=30\\x=-38\end{matrix}\right.\)

Vậy: x∈{30;-38}

d) Ta có: \(15-\left|2-x\right|=\left(-2\right)^2\)

\(\Leftrightarrow15-\left|2-x\right|=4\)

\(\Leftrightarrow\left|2-x\right|=11\)

\(\Leftrightarrow\left[{}\begin{matrix}2-x=11\\2-x=-11\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-9\\x=13\end{matrix}\right.\)

Vậy: x∈{-9;13}

e) Ta có: \(\left|15-x\right|+\left|-25\right|=\left|-55\right|\)

\(\Leftrightarrow\left|15-x\right|+25=55\)

\(\Leftrightarrow\left|15-x\right|=30\)

\(\Leftrightarrow\left[{}\begin{matrix}15-x=30\\15-x=-30\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-15\\x=45\end{matrix}\right.\)

Vậy: x∈{-15;45}

g) Ta có: \(\left|17-\left(-4\right)\right|+\left|-24-\left(-5\right)\right|=\left|-x+3\right|\)

\(\Leftrightarrow\left|17+4\right|+\left|-24+5\right|=\left|3-x\right|\)

\(\Leftrightarrow\left|3-x\right|=40\)

\(\Leftrightarrow\left[{}\begin{matrix}3-x=40\\3-x=-40\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-37\\x=43\end{matrix}\right.\)

Vậy: x∈{-37;43}

1) 40 + 15 + (-10) + (-15)                     2) -13 + (-750) + (-17) + 750                    3) (35 - 17) + (17 + 120 - 35)

= 40 + 15 - 10 - 15                               = -13 - 750 - 17 + 750                               = 35 - 17 + 17 + 120 - 35

= (40 - 10) + (15 - 15)                          = (-13 - 17) + (-750 + 750)                        = (35 - 35) + (-17 + 17) + 120

= 30                                                     = -30                                                          = 120

4) (55 + 45 + 15) - (15 - 55 + 45)               5) -(12 + 21 - 23) - (23 - 21 + 10)             6) (2020 - 79 + 15) - (-79 + 15)

= 55 + 45 + 15 - 15 + 55 - 45                     = -12 -21 + 23 - 23 + 21 - 10                    = 2020 - 79 + 15 + 79 - 15

= (45 - 45) + (15 - 15) + (55 + 55)              = (-12 - 10) + (-21 + 21) + (23 - 23)          = 2020 + (-79 + 79) + (15 - 15)

= 110                                                          = -22                                                         = 2020

7) -(515 - 80 + 91) - (2010 + 80 - 91)                     8) 25 - (-17) + 24 - 12               9) 235 - (34 + 135) - 100        

= -515 + 80 - 91 - 2010 - 80 + 91                           = 25 + 17 + 24 - 12                   = 235 - 34 - 135 - 100

= (-515 -2010) + (80 - 80) + (-91 + 91)                   = 54                                           = -34

= -2525       

10) (13 + 49) - (13 - 135 + 49)

= 13 + 49 - 13 + 135 - 49

= (13 - 13) + (49 - 49) +135

= 135                          

tự tính 

~HT~

25.3-x=104

75-x=104

x=75-104

x=-29

3(5x-15)-52=68

3(5x-15)=68+52

3(5x-15)=120

5x-15=120:3

5x-15=40

5x=40+15

5x=55

x=55:5

x=11

5(x+35)=515

x+35=515:5

x+35=103

x=103-35

x=68