a.\(3+x=-8\)
\(x=-8-3\)
\(x=-11\)
b.\(\left(35+x\right)-12=27\)
\(35+x=27+12\)
\(35+x=39\)
\(x=39-35\)
\(x=4\)
c.\(2^x+15=31\)
\(2^x=31-15\)
\(2^x=16\)
\(2^x=2^4\)
\(x=4\)

câu a : 

3 + x = -8

x = -8 - 3

x = -11

câu b : 

(35 + x) - 12 = 27

35 + x = 39

x = 39 - 35

x = 4

câu c : 

2^x + 15 = 31

2^x = 31 - 15

2^x = 16

x = \(\sqrt{16}\) = 4

a) 3 + x = - 8 

           x = - 8 - 3 

           x = -11

Vậy x = -11

b) ( 35 + x ) - 12 = 27 

     35 + x            = 27 + 12 

     35 + x            =  39 

             x             = 39 - 35 

             x              = 4 

            Vậy x = 4

Dấu này  * là dấu gì vậy bạn 

Bài 6:

a)\(\left(-18\right)-\left(-3\right)-12\)

\(=\left(-18\right)+3-12\)

\(=-15-12\)

\(=-27\)

b)\(85.\left(35-27\right)-35.\left(85-27\right)\)

\(=85.35-85.27-35.85+35.27\)

\(=85.\left(35-27-35\right)+35.27\)

\(=85.\left(-27\right)+35.27\)

\(=27.\left(-85+35\right)\)

\(=27.\left(-50\right)\)

\(=-1350\)

c)\(\left(-45\right).69+31.\left(-45\right)\)

\(=\left(-45\right).\left(69+31\right)\)

\(=\left(-45\right).100\)

\(=-4500\)

Bài 7:

a)\(\left(2-x\right)+10=-14\)

\(\Rightarrow2-x=-24\)

\(\Rightarrow x=26\)

b)\(14.\left|x\right|=28\)

\(\Rightarrow\left|x\right|=2\)

\(\Rightarrow\orbr{\begin{cases}x=2\\x=-2\end{cases}}\)

c)\(31-\left(17+x\right)=55\)

\(\Rightarrow17+x=-24\)

\(\Rightarrow x=-41\)

(-18)-(-3)-12=-27

85.(35-27)-35.(85-27)=-1350

(-45).69+31.(-45)=-4500

(2-x)+10=-14

\(\Leftrightarrow\)(2-x)=-14-10

\(\Leftrightarrow\)2-x=-24

\(\Rightarrow\)x=2-(-24)

\(\Rightarrow\)x=26

14.lxl=28

\(\Leftrightarrow\)lxl=28:14

\(\Leftrightarrow\)lxl=2

\(\Rightarrow\)x=-2

\(\left|x+12\right|-13=27\Leftrightarrow\left|x+12\right|=40\)

\(\Leftrightarrow\orbr{\begin{cases}x+12=40\\x+12=-40\end{cases}\Leftrightarrow\orbr{\begin{cases}x=28\\x=-52\end{cases}}}\)

\(35+26-\left|16+x\right|=138\)

\(\Leftrightarrow61-\left|16+x\right|=138\)

\(\Leftrightarrow\left|16+x\right|=-77\left(ktm\right)\)

Vậy không có x thỏa mãn

a,

=85.35-85.27-35.85+35.27

=85.35+85.(-27)-35.85+35.27

=85[35+(-27)+(-35)]+35.27

=85.(-27)+35.27

=-85.27+35.27

=27.[(-85)+35]

=27.(-50)

=-1350

các câu còn lại cũng vậy

a, 85 x ( 35- 27 ) - 35 x ( 35 - 27 )

85 x 8 - 35 x 8

8 x ( 85 - 35 ) 

8 x 50 = 400

b, ( -45 ) x 69 + 30 x ( -45 ) +( -45)

( -45 ) x ( 69 + 30 + 1)

-45 x 100 = -4500

c , 26 + 7 x ( 4 - 12 )

26 + 7 x ( - 8 )

26 + ( -56 )=(- 30)

d , 127 - 18 x ( 5 + 6 )

127 - 18 x 11

127 - 180 + 18

-53 + 18 = - 35

a.85x(35-27)-35x(85-27)

=85x8-35x58

=680-2030

=(-1350)

b.(-45)x69+30x(-45)+(-45)

=(-3105)+(-1350)+(-45)

=1800+(-45)

=1755

c.26+7x(4-12)

=26+7x(-8)

=26+(-56)

=(-30)

d.127-18x(5+6)

=127-18x11

=127-198

=(-71)

li-ke cho mình nha bạn

785-954 = ... cảm ơn

e , 12 x 35 + 35 x 182 - 35 x 94 
=    35 x ( 12 + 182 - 94 )
=    35 x       100
=         3500.

n , 19 x 27 + 47 x 81 + 19 x 20
=   19 x 27 + 19 x 20 + 47 x 81 
=   19 x ( 27 + 20 ) + 47 x 81
=   19 x        47      + 47 x 81
=    47 x ( 19 + 81 )
=    47 x     100
=       4700. 
T I C K cho mik nha !
~ HT ~      

\(\frac{x}{27}=\frac{12}{18}\)

Vì \(\frac{x}{27}=\frac{12}{18}\Rightarrow x\cdot18=27\cdot12\)

\(\Rightarrow x=\frac{27\cdot12}{18}=18\)

\(\frac{35}{49}=\frac{10}{x}\)

Vì \(\frac{35}{49}=\frac{10}{x}\Rightarrow35\cdot x=49\cdot10\)

\(\Rightarrow x=\frac{49\cdot10}{35}=14\)

1).( 27,56 x 35 ) + ( 27,56 x 67 ) - ( 27,56 x 2)

= (964 + 1846,52) - 55,12

=2810,52 - 55,12

= 2755,4

2).( 4x 35 ) x ( 25 x 5 ) x 2

= ( 140 x 125 ) x2

= 17500 x 2

=35000

4). 3/10

5). 1188

6).  61/6

1)2756   2)35000   3)0   4)3/10   5)10/1/6

1,2755,4

2,35000

3,0

4,\(\frac{3}{10}\)

5,1188

6,\(\frac{61}{6}\)