\(\frac{23+x}{40+x}=\frac{3}{4}\)

\(\Leftrightarrow4\left(23+x\right)=3\left(40+x\right)\)

\(\Leftrightarrow92+4x=120+3x\)

\(\Leftrightarrow4x-3x=120-92\)

\(\Leftrightarrow x=28\)

 suy ra (23+n).4=(40+n).3

suy ra 92+4n=120+3n

suy ra 4n-3n=120-92

suy ra n=28

\(\frac{23+n}{40+n}=\frac{3}{4}\)

\(\Leftrightarrow4\left(23+n\right)=3\left(40+n\right)\)

\(\Leftrightarrow92+4n=120+3n\)

\(\Rightarrow4n-3n=120-92\)

\(n=28\)

vậy n=28

nhớ kb và k nha

\(\frac{23+n}{40+n}=\frac{3}{4}\)

\(\Leftrightarrow\left(23+n\right).4=\left(40+n\right).3\)

      \(23.4+4n=40.3+3n\)

      \(92+4n=120+3n\)

      \(4n-3n=120-92\)

      \(n=28\)

Vậy n =28 

\(a.\dfrac{12+x}{42}=\dfrac{35}{42}\Leftrightarrow12+x=35\Leftrightarrow x=23\)

\(b.\dfrac{25-x}{40}=\dfrac{3}{8}\Leftrightarrow\dfrac{25-x}{40}=\dfrac{15}{40}\Leftrightarrow25-x=15\Leftrightarrow x=10\)

\(c.\dfrac{13+x}{20}=\dfrac{3}{4}\Leftrightarrow\dfrac{13+x}{20}=\dfrac{15}{20}\Leftrightarrow13+x=15\Leftrightarrow x=2\)

\(d.\dfrac{23-x}{25}=\dfrac{20}{25}\Leftrightarrow23-x=20\Leftrightarrow x=3\)

Ta có  \(\frac{23+n}{40+n}=\frac{3}{4}\) 

\(\Rightarrow\left(23+n\right)\times4=\left(40+n\right)\times3\)

\(\Rightarrow92+4n=120+3n\) 

\(\Rightarrow4n-3n=120-92\) 

\(\Rightarrow1n=28\)

\(\Rightarrow x=28\in Z\) 

Vậy x = 28

Thank you, cảm ơn bạn rất nhiều!!!!!!!!!!!!!!!!!

Câu 1 :

a ) (-11)*3 + (-5)-20117-0 -(-10)

 = -33+ (-5) -0 - (-10)

= -38-0-(-10)

=-38-(-10)

=-28

b) 25 *(23-17)-25*(23-17)

= 25*6-25*6

=150-150

=0

c) 100[5*(9-11)^2+(-4)^2

=100*[5*(-2)^2 +16

=100*(20+16)

=100*36

=3600

Câu 2: 

2*|x-2|=40

|x-2| = 40/2

|x- 2 | = 20

TH1=>  x-2 =20=> x= 22

TH2 => x-2 = -20=> x = -20

kb vs mk nha 

2)2|x-2|=40=>|x-2|=20=>x-2=20 hoặc x-2=-20=>x=22 hoặc x=-18

minh ko biet xin loi ban nha!

minh ko biet xin loi ban nha!

minh ko biet xin loi ban nha!

minh ko biet xin loi ban nha!

=> 143 - 3 chia hết cho x

140 chia hết cho x

=> 123 - 23 chia hết cho x 

100 chia hết cho x

=> x thuộc ƯC(140 ; 100)

UCLN(140 ; 100) = 20 

Vậy x thuộc {1;2;4;5;10;20} 

a) x = 190            

b) x = 344           

c) x = 4                

d) x = 20