a: 1,995:x=7,98

nên x=0,25

c: 120,4+x=268,26-13

=>x+120,4=255,26

hay x=134,86

a: 1,995:x=7,98

=>  x=0,25
câu b ko nhìn thấy rõ đề

c: 120,4+x=268,26-13

=>x+120,4=255,26

=> x=134,86

B

b

B3: 

a) x = 0

b) 9

B4 :

a) x = 1,2,3

b) x = 0,1,2

B5:

0,21; 0,215; 0,22

cho xin phép tính vs ạ

a: \(x+\dfrac{3}{9}=\dfrac{7}{6}\cdot\dfrac{2}{3}\)

=>\(x+\dfrac{1}{3}=\dfrac{14}{18}=\dfrac{7}{9}\)

=>\(x=\dfrac{7}{9}-\dfrac{1}{3}=\dfrac{7}{9}-\dfrac{3}{9}=\dfrac{4}{9}\)

b: \(x-\dfrac{2}{3}=\dfrac{1}{8}:\dfrac{5}{4}\)

=>\(x-\dfrac{2}{3}=\dfrac{1}{8}\cdot\dfrac{4}{5}=\dfrac{1}{10}\)

=>\(x=\dfrac{1}{10}+\dfrac{2}{3}=\dfrac{3+20}{30}=\dfrac{23}{30}\)

TThế giới oi oi oi 

`#3107.101107`

a)

\(x+x+\dfrac{1}{2}\times\dfrac{2}{5}+x+\dfrac{8}{10}=121\\3x+\dfrac{1}{5}+\dfrac{4}{5}=121\\ 3x+1=121\\ 3x=121-1\\ 3x=120\\ x=40 \)

Vậy, `x = 40`

b)

\(\dfrac{12+x}{42}=\dfrac{5}{6}\\ \dfrac{12+x}{42}=\dfrac{35}{42}\\ \dfrac{12+x}{42}-\dfrac{35}{42}=0\\ \dfrac{12+x-35}{42}=0\\ \dfrac{x-\left(35-12\right)}{42}=0\\ \dfrac{x-23}{42}=0\\ x-23=0\\ x=23\)

Vậy,` x = 23.`

a: \(x+x+\dfrac{1}{2}\cdot\dfrac{2}{5}+x+\dfrac{8}{10}=121\)

=>\(3x+\dfrac{1}{5}+\dfrac{4}{5}=121\)

=>3x+1=121

=>3x=120

=>x=40

b: \(\dfrac{x+12}{42}=\dfrac{5}{6}\)

=>\(x+12=42\cdot\dfrac{5}{6}=35\)

=>x=35-12=23

`a, x +1,4xx5,6=15,96`

`x+7,84=15,96`

`x=15,96-7,84`

`x=8,12`

`b,x-4,2xx5,7=255,3`

`x-23,94=255,3`

`x=255,3+23,94`

`x=279,24`

a)X = 55,78

b)X = 5,42

c)X = 23,4

d) X = 5,508

a)X = 55,78

b)X = 5,42

c)X = 23,4

d) X = 5,508

\(a,x-21,7=34,08\\ \Rightarrow x=34,08+21,7\\ \Rightarrow x=55,78\\ b,x+4,08=9,5\\ \Rightarrow x=9,5-4,08\\ \Rightarrow x=5,42\\ c,x\times3,6=84,24\\ \Rightarrow x=84,24:3,6\\ \Rightarrow x=23,4\\ d,x:1,8=3,06\\ \Rightarrow x=3,06\times1,8\\ \Rightarrow x=5,508\)

a,x−21,7=34,08⇒x=34,08+21,7⇒x=55,78b,x+4,08=9,5⇒x=9,5−4,08⇒x=5,42c,x×3,6=84,24⇒x=84,24:3,6⇒x=23,4d,x:1,8=3,06⇒x=3,06×1,8⇒x=5,508

Mình cần gấp!!!!

Bài 1: 

a: x/33=4

nên x=4x33=132

b: 5/x=1/2

=>5/x=5/10

hay x=10

Bài 2:

Gọi tử là x

Mẫu là 180-x

Theo đề, ta có: \(\dfrac{x}{180-x}=\dfrac{4}{5}\)

=>5x=720-4x

=>9x=720

hay x=80

Vậy: Phân số cần tìm là 80/100