Mik cảm ơn hứa cho 5* ạ

$\text{a) 250 : ( 10 - x ) = 25}$

$\text{10 - x = 250 : 25}$

$\text{10 - x = 10}$

$\text{x = 10 - 10}$

⇒ $\text{x = 0.}$

`----`

$\text{b) 3x - 2018 : 2 = 23}$

$\text{3x - 1009 = 23}$

$\text{3x = 23 + 1009}$

$\text{3x = 1032}$

$\text{x = 1032 : 3}$

⇒ $\text{x = 344.}$

`----`

$\text{c) ( 9x - 21 ) : 3 = 2}$

$\text{9x - 21 = 2 . 3}$

$\text{9x - 21 = 6}$

$\text{9x = 6 + 21}$

$\text{9x = 27}$

$\text{x = 27 : 9}$

⇒ $\text{x = 3.}$

`----`

$\text{d) 53 (9 - x) = 53}$

$\text{9 - x = 53 : 53}$

$\text{9 - x = 1}$

$\text{x = 9 - 1}$

⇒ $\text{x = 8.}$

`----`

$\text{e) 91 - 5 . ( 5 + x ) = 61}$

$\text{5 . ( 5 + x ) = 91 - 61}$

$\text{5 . ( 5 + x ) = 30}$

$\text{5 + x = 30 : 5}$

$\text{5 + x = 6}$

$\text{x = 6 - 5}$

⇒ $\text{x = 1.}$

`----`

$\text{f) [ 195 - ( 3x - 27 )] . 39 = 4212}$

$\text{195 - ( 3x - 27 ) = 4212 : 39}$

$\text{195 - ( 3x - 27 ) = 108}$

$\text{3x - 27 = 195 - 108}$

$\text{3x - 27 = 87}$

$\text{3x = 87 + 27}$

$\text{3x = 114}$

$\text{x = 114 : 3}$

⇒ $\text{x = 38.}$