-12x+60+21-7x=5

-12x-7x=-60-21+5

-19x=-76

x=4

-12.x + 12.5+7.3-7.x=5

-12.x+ 60+21-7.x=5

-19.x=76

=> không có x

<=>(-12)(x-5)+7(3-x)=-(19x-81)

=>-(19x-81)=5

<=>81-19x=5

=>-19x=-76

=>x=(-76):(-19)

=>x=4

- 12.( x - 5 ) + 7.( 3 - x ) = 5

=> - 12x + 60 + 21 - 7x = 5

=> ( - 12x - 7x ) + 60 + 21 = 5

=> - 19x + 81 = 5

=> - 19x = 5 - 81

=> - 19x = - 76

=> x = ( - 76 ) : ( - 19 )

=> x = 4

Vậy x = 4

-12x+60+21=5

-12x+81=5

-12x=-76

x=19/3         k nha

(-12) (x - 5) + 7(3 - x) = 5

=> -12x + 60 + 21 - 7x - 5 = 0

=> -19x + 76 = 0

=> -19x = -76

=> x = 4

-12(x-5)+7(3-x)=5

<=>(-12x)-(-60)+21-7x=5

<=>(-12x)+60+21-7x=5

<=>(-12x-7x)+81=5

<=>(-19x)=-76<=>x=4

 vậy x=4

-12x+60+21-7x-5=0

19x=76

x=76/19

x = 4 phai ko

42+(3x+7):2=2^5+3^4

 42+(3x+7):2=32+81

 42+(3x+7):2=113

      (3x+7):2=113-42

      (3x+7):2=71

          3x+7=71x2

          3x+7=142

              3x=142:7

              3x=142/7

                x=142/7:3

                x=142/21

\(\frac{6}{5}< \frac{x-3}{2}< \frac{12}{5}\)

\(=\frac{6.2}{5.2}< \frac{x.5-3}{2.5}< \frac{12.2}{5.2}\)

\(=\frac{12}{10}< \frac{x.5-3}{10}< \frac{24}{10}\)

\(x\)nhân 5 - 3 chỉ có thể bằng 17 vì 17 + 3 = 20 mà 20 chia hết cho 5.

vậy \(x\)= 20 : 5 = 4

Đ/s : x = 4