20-[7.(x-3)+4]=2
=>7.(x-3)+4 =20-2
=>7.(x-3)+4 =18
=>7(x-3) =18-4
=>7(x-3) =14
=>x-3 =14:7
=>x-3 =2
=>x =2+3
=>x =5
20-[7.(x-3)+4]=2
[7,(x-3)+4]=20-2
[7.(x-3)+4]=18
7.(x-3) =18-4
7.(x-3) =14
(x-3) =14:7
(x-3) =2
x =2+3
x =5
20 - [ 7 × ( x - 3 ) + 4 ] = 2
7 × ( x - 3 ) + 4 = 20 - 2
7 × ( x - 3 ) + 4 = 18
7 × ( x - 3 ) = 18 - 4
7 × ( x - 3 ) = 14
x - 3 = 14 ÷ 7
x - 3 = 2
x = 2 + 3 = 5
Vậy x = 5