2 x (1/4 - 3x) = 1/5 - 4x
=> 1/2 . 6x = 1/5 - 4x
=> 1/2 - 1/5 = 6x - 4x
=> 3/10 = 2x
=> x = 3/20
tiick mk nha
2 \(\times\) (1/4 - 3x) = 1/5 - 4x
-> (2\(\times\) 1/4) - (2 \(\times\) 3x) = 1/5 - 4x
-> 1/2 - 6x = 1/5 - 4x
->1/2 - 6x - 1/5 + 4x = 0
->3/10 - 2x = 0
->2x = 3/10
->x = 3/20
Vậy....