X = 34000 . 

X = 34 . 

x : 105 = 323 ( dư 85 )

x = 323 . 105 + 85

x = 34 000

Vậy x = 34 000

x + 32 x 327 = 17985 

=> x  + 10464 = 17985 

=> x =  17985 - 10464

=> x =7521

x + 32 x 327 = 17985

x + 32 = 17985 : 327

x + 32 = 55

x = 55 - 32

x = 23

x  :105 = 323 ( dư 85 )

x = ( 323 - 85 ) x 105 

x = 24990

15126 : x = 438 ( dư 234 )

x = ( 15126 - 234 ) : 438

x = 14892 : 438 

x = 34

\(\dfrac{x}{5}=\dfrac{26}{65}\)

\(\dfrac{x}{5}=\dfrac{2}{5}\)

\(x=2\)

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\(\dfrac{3}{x}=\dfrac{51}{85}\)

\(\dfrac{3}{x}=\dfrac{3}{5}\)

`x=5`

\(+,\dfrac{x}{5}=\dfrac{26}{65}\\ =>x=\dfrac{5\times26}{65}=2\\+, \dfrac{3}{x}=\dfrac{51}{85}\\ =>x=\dfrac{3\times85}{51}=5\)

\(\dfrac{x}{5}=\dfrac{26}{65}\)

\(\Leftrightarrow65x=130\)

\(\Leftrightarrow x=2\)

\(\dfrac{3}{x}=\dfrac{51}{85}\)

\(\Leftrightarrow51x=255\)

\(\Leftrightarrow x=5\)

`x/5=26/65`

`65xx x=5xx26`

`65xx x=130`

`x=130:65=2`

`3/x=51/85`

`51xx x=3xx85`

`51xx x=255`

`x=255:51=5`

328185

507195

\(=438\times\left(66+33+1\right)\\ =438\times100\\ =43800\)

=438 x (66+33+1)

=438 x 100

=43800

\(a,\dfrac{x}{4}=\dfrac{15}{20}\\ \Rightarrow\dfrac{x}{4}=\dfrac{3}{4}\\ \Rightarrow x=3\\ b,\dfrac{15}{x}=\dfrac{25}{35}\\ \Rightarrow\dfrac{15}{x}=\dfrac{5}{7}\\ \Rightarrow\dfrac{15}{x}=\dfrac{15}{21}\\ \Rightarrow x=21\\ c,\dfrac{x}{5}=\dfrac{26}{65}\\ \Rightarrow\dfrac{x}{5}=\dfrac{2}{5}\\ \Rightarrow x=2\\ d,\dfrac{3}{x}=\dfrac{51}{85}\\ \Rightarrow\dfrac{3}{x}=\dfrac{3}{5}\\ \Rightarrow x=5\)

a,x4=1520⇒x4=34⇒x=3b,15x=2535⇒15x=57⇒15x=1521⇒x=21c,x5=2665⇒x5=25⇒x=2d,3x=5185⇒3x=35⇒x=5

Ta có:

\(\frac{65}{85}=\frac{13}{17}\)

\(\frac{84}{105}=\frac{4}{5}\)

Vì \(\frac{13}{17}\ne\frac{4}{5}\)

=>\(\frac{65}{87}\ne\frac{84}{105}\)