2x - 3 + 5x = 4x + 12
7x - 3 = 4x + 12
7x-4x= 12+3
3x=15
x=15:3
x=5
2x-[3-5x]=4[x+3]
=>7x-3=4x+3
=>7x-3=4x+12
=>7x-4x=3+12
=>3x=15
=>x=5
sửa lại
2x-[3-5x]=4[x+3]
=>7x-3=4(x+3)
=>7x-3=4x+12
=>7x-4x=3+12
=>3x=15
=>x=5
2x - 3 + 5x = 4x + 12
7x - 3 = 4x + 12
7x-4x= 12+3
3x=15
x=15:3
x=5