Giải thích các bước giải:
`1) (x - 12) - (2x + 31) = -6 - 5`
`=>x-12-2x-31=-11`
`=>x-2x-12-31=-11`
`=>x.(1-2)-(12+31)=-11`
`=>x.(-1)-43=-11`
`=>x.(-1)=-11+43`
`=>x.(-1)=32`
`=>x=32:(-1)`
`=>x=-32`
`2) -2 . (x + 7) + 3 . (x - 2) = -2`
`=>-2.x+(-14)+3.x-6=-2`
`=>-2.x+3.x+(-14)-6=-2`
`=>x.(-2+3)-20=-2`
`=>x.1=-2+20`
`=>x.1=18`
`=>x=18:1`
`=>x=18`