x + x * 1/4 : 2/7 + x : 2/9 = 255

x + x * 1/4 * 7/2 + x * 9/2 = 255

x + x * 7/8 + x * 9/2 = 255

x * ( 1 + 7/8 + 9/2 ) = 255

x * (8/8 + 7/8 + 36/8 ) = 255

x * 51/8 = 255

x = 255 : 51/8

x = 255* 8/51

x = 40

Chúc bạn học tốt!

x + x × 1/4 : 2/7 + x : 2/9 = 255

x + x × 1/4 × 7/2 + x × 9/2 = 255

x + x × 7/8 + x × 9/2 = 255

x × (1 + 7/8 + 9/2) = 255

x × (8/8 + 7/8 + 36/8) = 255

x × 51/8 = 255

x = 255 : 51/8

x = 255 × 8/51

x = 40

x + x * 1/4 : 2/7 + x : 2/9 = 255

x + x * 1/4 * 7/2 + x * 9/2 = 255

x + x * 7/8 + x * 9/2 = 255

x * ( 1 + 7/8 + 9/2 ) = 255

x * (8/8 + 7/8 + 36/8 ) = 255

x * 51/8 = 255

x = 255 : 51/8

x = 255* 8/51

x = 40

x + x × 1/4 : 2/7 + x : 2/9 = 255

x + x × 1/4 × 7/2 + x × 9/2 = 255

x + x × 7/8 + x × 9/2 = 255

x × (1 + 7/8 + 9/2) = 255

x × (8/8 + 7/8 + 36/8) = 255

x × 51/8 = 255

x = 255 : 51/8

x = 255 × 8/51

x = 40

x + x × 1/4 : 2/7 + x : 2/9 = 255

x + x × 1/4 × 7/2 + x × 9/2 = 255

x + x × 7/8 + x × 9/2 = 255

x × (1 + 7/8 + 9/2) = 255

x × (8/8 + 7/8 + 36/8) = 255

x × 51/8 = 255

x = 255 : 51/8

x = 255 × 8/51

x = 40

Vậy x = 40

40

Lời giải:

$x+x\times \frac{1}{4}: \frac{2}{7}+x: \frac{2}{9}=255$

$x+x\times \frac{7}{8}+x\times \frac{9}{2}=255$

$x\times (1+\frac{7}{8}+\frac{9}{2})=255$

$x\times \frac{51}{8}=255$

$x=255: \frac{51}{8}=40$

\(x+x.\frac{1}{4}:\frac{2}{7}+x:\frac{2}{9}=255\) 

\(\Leftrightarrow x+x\frac{1}{4}.\frac{7}{2}+x.\frac{9}{2}=255\)   

\(\Leftrightarrow x\left(1+\frac{1}{4}.\frac{7}{2}+\frac{9}{2}\right)=255\)

\(\Leftrightarrow x.\frac{51}{8}=255\) 

\(\Leftrightarrow x=40\)

\(x +x\cdot\frac{1}{4}\text{ : }\frac{2}{7}+x\text{ : }\frac{2}{9}=255\)

\(x+x\cdot0,25\text{ : }0,285714286+x\text{ : }0,222222222=255\)

\(x+x\cdot\left(0,25\text{ : }0,285714286\right)+x\text{ }\text{ : }0,222222222=255\)

\(x+x\cdot0,874999999+x\text{ : }0,222222222=255\)

\(x\cdot3\cdot\left(0,874999999\text{ : }0,222222222\right)=255\)

\(x\cdot3\cdot3,9375=255\)

\(x\cdot3=255\text{ : }3,9375\)

\(x\cdot3=64,7619048\)

\(x=64,7619048\text{ : }3\)

\(x=21,5873016\)

gokazaru xuất sắc tất cả các môn

       \(x+x.\frac{1}{4}:\frac{2}{7}+x:\frac{2}{9}=255\)

\(=x+x.\left(\frac{1}{4}:\frac{2}{7}\right)+x:\frac{2}{9}=255\)

\(=x+x.\frac{7}{8}+x:\frac{2}{9}=255\)

\(=x+x.\frac{7}{8}+x.\frac{9}{2}=255\)

\(=x+x.\left(\frac{7}{8}+\frac{9}{2}\right)=255\)

\(=x+x.\frac{43}{8}=255\)

\(\Leftrightarrow x=40\)

chúc bạn học giỏi

\(x+x\times\frac{1}{4}:\frac{2}{7}+x:\frac{2}{9}=255\)

\(x+x\times\frac{1}{4}\times\frac{7}{2}+x\times\frac{9}{2}=255\)

\(x\times\left(1+\frac{1}{4}\times\frac{7}{2}+\frac{9}{2}\right)=255\)

\(x\times\frac{51}{38}=255\)

\(x=255:\frac{51}{38}\)

\(x=190\)

\(x+x.\frac{1}{4}:\frac{2}{7}+x:\frac{2}{9}=255\)

\(\Rightarrow x+x.\frac{1}{4}.\frac{7}{2}+x.\frac{9}{2}=255\)

\(\Rightarrow x+x.\frac{7}{8}+x.\frac{9}{2}=255\)

\(\Rightarrow x.\left(1+\frac{7}{8}+\frac{9}{2}\right)=255\)

\(\Rightarrow x.\frac{51}{8}=255\)

\(\Rightarrow x=255:\frac{51}{8}\)

\(\Rightarrow x=40\)

Vậy x = 40

_Chúc bạn học tốt_

a) \(x+x\times\frac{1}{4}\div\frac{2}{7}+x\div\frac{2}{9}=255\)

\(\Rightarrow x+x\times\frac{1}{4}\times\frac{7}{2}+x\times\frac{9}{2}=255\)

\(\Rightarrow x+x\times\frac{7}{8}+x\times\frac{9}{2}=255\)

\(\Rightarrow x\times\left(1+\frac{7}{8}+\frac{9}{2}\right)=255\)

\(\Rightarrow x\times\frac{51}{8}=255\)

\(\Rightarrow x=255\div\frac{51}{8}\)

\(\Rightarrow x=40\)

Vậy x = 40

b) \(1\frac{1}{21}\div\left(15,75-15\frac{1}{5}\right)+2\frac{1}{12}\div\left(7\frac{3}{4}-7,25\right)\)

\(=\frac{22}{21}\div\left(15,75-\frac{76}{5}\right)+\frac{25}{12}\div\left(\frac{31}{4}-7,25\right)\)

\(=\frac{22}{21}\div\frac{11}{20}+\frac{25}{12}\div\frac{1}{2}\)

\(=\frac{40}{21}+\frac{25}{6}\)

\(=\frac{85}{14}\)

_Chúc bạn học tốt_

X + X x 1/4 : 2/7 + x : 2/9 = 225

X + X x 1/4 x 7/2 + X x 9/2 = 225

X + X x 7/8 + X x 9/2 = 225

X x ( 1 + 7/8 + 9/2 ) = 225

X x 51/8 = 225

X = 225 : 51/8

X = 600/17