x+6.20=120.10

x+120=1200

x=1200-120

x=1080

x + 6 x 20 = 120 x 10

x + 120 = 1 200

x = 1 200 - 120

x = 1 080

120 - ( x + 5 ) : 4 x 10 = 20

120 - ( x + 5 ) : 4 = 20 : 10

120 - ( x + 5 ) : 4 = 2

120 - ( x + 5 ) = 2 x 4

120 - ( x + 5 ) = 8

x + 5 = 120  - 8

x + 5 = 112

      x = 112 - 5

      x = 107

( x + 5 ) : 4 x 10 = 120 - 20 

( x + 5 ) : 4 x 10 = 100 

( x + 5 ) : 4        = 100 : 10 

( x + 5 ) : 4        =   10 

x + 5                  = 10 x 4 

x + 5 = 40

x       = 40 - 5 

x       = 35 

Vậy x là 35

TL

a)    5x + 20 = 110      

<=> x = 90 : 5 = 18

 b) x + 18 = - 13 

 <=> x = - 31

  c) 120 - x =  50   

   <=> x = 70     

 d) 10 - x = -29  

     <=>  x = 39

e) - x + 31 = 61

<=> x = -30

f) -85 - x = --70

<=> x = 15

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\(120⋮x;90⋮x\)

\(\Rightarrow x\inƯC\left(120;90\right)=\left\{1;2;3;5;6;10;15;30\right\}\)

Mà \(10< x< 20\)

\(\Rightarrow x\in\left\{15\right\}\)

Vậy x = 15

30 dễ quớ 

10 x 20 = 200,

120+180= 300

xong rồi đó tick cho mình nha!

10x20=200

120+180=300

Lớp 6 rồi mà gà quá :v

Ta có:

10+20+30=(120:(x-6)+24)

=>(120:(x-6)+24)=60

=> 120:(x-6)=36

=> x-6=10/3

=> x=28/3

Ta có :

10 + 20 = 30 = [ 120 : ( x - 6 ) + 24 ]

Suy ra [ 120 : ( x - 6 ) + 24 ] = 60

Suy ra 120 : ( x - 6 ) = 36

Suy ra x - 6 = 10/3

Suy ra x = 28/3

120 x 13 + 120 x 87 - 120 x 10 = ?

= 120 x { 13 + 87 - 10 }

= 120 x  90

= 10800

120 x 13 + 120 x 87 - 120 x 10

= 120 x ( 13 + 87 - 10 )

= 120 x 90

= 10 800

Ta có : \(\frac{10-x}{100}+\frac{20-x}{110}+\frac{30-x}{120}=3\)

<=> \(\frac{10-x}{100}+\frac{20-x}{110}+\frac{30-x}{120}-3=0\)

<=> \(\left(\frac{10-x}{100}-1\right)+\left(\frac{20-x}{110}-1\right)+\left(\frac{30-x}{120}-1\right)\)= 0

<=> \(\left(\frac{-90-x}{100}\right)+\left(\frac{-90-x}{110}\right)+\left(\frac{-90-x}{120}\right)=0\)

<=> (-90-x) \(\left(\frac{1}{100}+\frac{1}{110}+\frac{1}{120}\right)=0\)

<=> -90- x = 0 vì \(\left(\frac{1}{100}+\frac{1}{110}+\frac{1}{120}\right)\ne0\) ( > 0)

<=> -x = 90

<=> x = -90

Vậy x = -90

(10-x)/100+(20-x)/110+(30-x)/120=3

=>(10-x)/100+(20-x)/110+(30-x)/120-3=0

=>(10-x)/100-1+(20-x)/110-1+(30-x)/120-1=0

=>(-90-x)/100+(-90-x)/110+(-90-x)/120=0

=.>(-90-x)(1/100+1/110+1/120)=0

=.>(-90-x)=0(vì(1/100+1/110+1/120)luôn>0)

=>x=-90

a) \(\left(2x-18\right):\left(-10\right)-34=2\)

\(\Rightarrow\left(2x-18\right):\left(-10\right)=2+34\)

\(\Rightarrow\left(2x-18\right):\left(-10\right)=36\)

\(\Rightarrow2x-18=36\cdot\left(-10\right)\)

\(\Rightarrow2x-18=-360\)

\(\Rightarrow2x=-360+18\)

\(\Rightarrow2x=-342\)

\(\Rightarrow x=-342:2\)

\(\Rightarrow x=-171\) 

b) \(120:\left(5x+20\right)-45=75\)

\(\Rightarrow120:\left(5x+20\right)=75+45\)

\(\Rightarrow120:\left(5x+20\right)=120\)

\(\Rightarrow5x+20=120:120\)

\(\Rightarrow5x+20=1\)

\(\Rightarrow5x=1-20\)

\(\Rightarrow5x=-19\)

\(\Rightarrow x=-\dfrac{19}{5}\)

QUY TẮC ⇒ TÍNH ĐƯỢC KẾT QUẢ BẰNG BAO NHIÊU RỒI CỘNG THÊM 100.

40 + 40 = 180