2806 : x = 103 ( dư 25 )

           x = ( 2806 - 25 ) : 103

           x = 2781 : 103 

           x = 27

\(\frac{x+50}{x+61}=\frac{x-15}{x-10}\)

\(\Leftrightarrow\left(x+50\right).\left(x-10\right)=\left(x-15\right).\left(x+61\right)\)

\(\Rightarrow x^2-10x+50x-500=x^2+61x-15x-915\)

\(\Rightarrow40x-500=46x-915\)

\(\Rightarrow415=6x\Rightarrow x=\frac{415}{6}\)

156 – ( x + 61) = 82

x + 61 = 156 – 82

x + 61 = 74

x = 74 – 61

x = 13.

\(4x=7y=3z\Rightarrow\dfrac{4x}{84}=\dfrac{7y}{84}=\dfrac{3z}{84}\\ \Rightarrow\dfrac{x}{21}=\dfrac{y}{12}=\dfrac{z}{28}=\dfrac{x+y+z}{21+12+28}=\dfrac{61}{61}=1\\ \Rightarrow\left\{{}\begin{matrix}x=21\\y=12\\z=28\end{matrix}\right.\)

a) \(-3x-61=5\)

\(-3x=5+61\)

\(-3x=66\)

\(x=66:-33\)

\(x=-22\)

-3x - 61 = 5

-3x = 5 + 61 = 66

x = 66 : ( -3 ) = -22

Tk
Cre: On the Hoidap247

\(\dfrac{x+35}{65}+\dfrac{x+39}{61}=\dfrac{x+43}{57}+\dfrac{x+47}{53}\)

\(\Leftrightarrow\dfrac{x+35}{65}+1+\dfrac{x+39}{61}+1=\dfrac{x+43}{57}+1+\dfrac{x+47}{53}+1\)

\(\Leftrightarrow\dfrac{x+100}{65}+\dfrac{x+100}{61}-\dfrac{x+100}{57}-\dfrac{x+100}{53}=0\)

\(\Leftrightarrow\left(x+100\right)\left(\dfrac{1}{65}+\dfrac{1}{61}-\dfrac{1}{57}-\dfrac{1}{53}\ne0\right)=0\Leftrightarrow x=-100\)

Ta có:

\(\dfrac{x+35}{65}+\dfrac{x+39}{61}=\dfrac{x+43}{57}+\dfrac{x+47}{53}\\ \Rightarrow\left(\dfrac{x+35}{65}+1\right)+\left(\dfrac{x+39}{61}+1\right)=\left(\dfrac{x+43}{57}+1\right)+\left(\dfrac{x+47}{53}+1\right)\\ \Rightarrow\dfrac{x+100}{53}+\dfrac{x+100}{61}=\dfrac{x+100}{57}+\dfrac{x+100}{53}\\ \Rightarrow\left(x+100\right)\left(\dfrac{1}{65}+\dfrac{1}{61}-\dfrac{1}{57}-\dfrac{1}{53}\right)=0\)

Ta thấy:

\(\dfrac{1}{65}< \dfrac{1}{57}\\ \dfrac{1}{61}< \dfrac{1}{53}\\ \Rightarrow\left(\dfrac{1}{65}+\dfrac{1}{62}\right)-\left(\dfrac{1}{57}+\dfrac{1}{53}\right)< 0\)

Hay \(\dfrac{1}{65}+\dfrac{1}{62}-\dfrac{1}{57}-\dfrac{1}{53}\ne0\)

\(\Rightarrow x+100=0\\ \Rightarrow x=0-100\\ \Rightarrow x=-100\)

 Vậy \(x=-100\)

Ta có: \(\dfrac{x+35}{65}+\dfrac{x+39}{61}=\dfrac{x+43}{57}+\dfrac{x+47}{53}\)

\(\Leftrightarrow\dfrac{x+100}{65}+\dfrac{x+100}{61}-\dfrac{x+100}{57}-\dfrac{x+100}{53}=0\)

\(\Leftrightarrow x+100=0\)

hay x=-100

a) 467 + x = 877 – 162

467 + x = 715

x = 715 – 467

x = 248

b) x – 214 = 61 + 345

x – 214 = 406

x = 406 + 214

x = 620

c) x : 5 = 10 × 2

x : 5 = 20

x = 20 × 5

x = 100

d) x × 4 = 30 – 10

x × 4 = 20

x = 20 : 4

x = 5

a) 156 - ( x + 61 ) = 82

x + 61 = 156 - 82

x + 61 = 74

x = 74 - 61

x = 13

b) 124 + ( 18 - x ) = 317

18 - x = 317 - 124

18 - x = 193

x = 18 - 193

x = -175