a) 123-5x-5.4=38

123-5x-20=38

103-5x=38

5x=103-38

x=(103-38):5=13

b)

(3.x-16).7^3=2.7^4

3x-16=2.7^4/7^3=2.7=14

3x=14+16=30

x=30/3=10

123 - 5 . ( x + 4 ) = 38

5 . ( x + 4 ) = 123 - 38

5 . ( x + 4 ) = 85

x + 4 = 85 : 5

x + 4 = 17

      x = 17 - 4

      x = 13

( 3x - 2⁴ ) . 7³ = 2 . 7⁴

( 3x - 16 ) . 343 = 2 . 2401

( 3x - 16 ) . 343 = 4802

3x - 16 = 4802 : 343

3x - 16 = 14

3x = 14 + 16

3x = 30

  x = 30 : 3

  x = 10

123 - 5( x + 4 ) = 38

=> 5( x + 4 ) = 123 - 38

=> x + 4 = 85 ÷ 5

=> x = 17 - 4 

=> x = 13

(3x - 2⁴ ) · 7³ = 2·7⁴

=> ( 3x - 16 ) = 2 . 7⁴ ÷ 7³

=> 3x - 16 = 14

=> 3x = 16 + 14

=> x = 30 ÷ 3 

=> x = 10

\(123-5\left(x+4\right)=38\\ 5\left(x+4\right)=85\\ x+4=17\\ x=13\)

\(123-5\left(x+4\right)=38\)

\(\Rightarrow123-5x-20=38\)

\(\Rightarrow-5x=-65\)

\(\Rightarrow x=13\)

Vậy: ...

\(123-5x-20=38\Leftrightarrow123-5x=58\Leftrightarrow5x=65\Leftrightarrow x=13\)

`123-5(x+4)=38`

`5x-20=123-38`

`5x-20=85`

`5x=85+20`

`5x=105`

`x=105:5`

`x=21`

123-5.(x+4)=38

         5x-20=123-38

         5x-20=85

               5x=85+20

               5x=105

                 x=105:5

                x=21

123 - 5 . ( x + 4 ) = 38

5 . ( x + 4 ) = 123 - 38

5 . ( x + 4 ) = 85

x + 4 = 85 : 5

x + 4 = 17

      x = 17 - 4

 => x = 13

123-5.(x+4)=38

=>5.(x-4)=123-38

=>5.(x-4)=85

=>x-4=85:5

=>x-4=17

=>x=17+4

=>x=21

123-5 . (x+4) =38

5.(x+4)=123-38

5.(x+4)=85

x+4=85:5

x+4=17

x=17-4

x=13
 

Giải:

\(123-5\left(x-4\right)=38\)

\(\Leftrightarrow5\left(x-4\right)=123-38\)

\(\Leftrightarrow5\left(x-4\right)=85\)

\(\Leftrightarrow x-4=\dfrac{85}{5}\)

\(\Leftrightarrow x-4=17\)

\(\Leftrightarrow x=17+4\)

\(\Leftrightarrow x=21\)

Vậy \(x=21\).

Chúc bạn học tốt!!!

123-5(x+4)=38

5(x+4)=38

5(x+4)=123-38

5(x+4)=85

x+4=85:5

x+4=17

x=17-4

x=13

Chúc bạn học tốt nha

123 - 5 . ( x + 4 ) = 38

         5 . ( x + 4 ) = 123-38

         5 . ( x + 4 ) = 85

         5 . ( x + 4 ) = 85

         ( x + 4 ) = 85 : 5

         ( x + 4 ) = 17

          x = 17 - 4

          x = 13

Vậy x=13

123 - 5 . ( x + 4 ) = 38

         5 . ( x + 4 ) = 123-38

         5 . ( x + 4 ) = 85

         5 . ( x + 4 ) = 85

         ( x + 4 ) = 85 : 5

         ( x + 4 ) = 17

          x = 17 - 4

          x = 13

123 - 5 . ( x + 4 ) = 38

5 . ( x + 4 ) = 123 - 38

5 . ( x + 4 ) = 85

x + 4 = 85 : 5

x + 4 = 17

x = 17 - 4

x = 13
 

\(123-5.\left(x+4\right)=38\)

               \(5.\left(x+4\right)=123-38\)

               \(5.\left(x+4\right)=85\)

                      \(x+4=85\div5\)

                      \(x+4=17\)

                      \(x=17-4\)

                      \(x=13\)

            Chúc bn hk tốt nhoa :) 

123-5.(x+4)=38

       5.(x+4)=123-38

       5.(x+4)=85

           x+4 =85:5

           x+4=17

           x    =17-4

           x    = 13

123-5.(x+4)=38

5.(x+4)=123-38

5.(x+4)=85

  x+4=85:5

 x+4 =17

 x     =17-4

 x         =13

Chúc bn học tốt

5*(x-4)=123-38

5*(x-4)=85

x-4=85:5

x-4=17

x=17+4

x=21

5*(x-4)=123-38

5*(x-4)=85

x-4=85:5

x-4=17

x=17+4

x=21

123 - 5.(x - 4) = 38

         5.(x - 4) = 123 - 38
         5.(x - 4) = 85

              x - 4 = 85 : 5

              x - 4 = 17

                   x = 17 + 4

                   x = 21