(2x-3y)-3(4x-2y)=2x-3y-12x+6y=-10x+3y
a-(2a+b)+2(a-2b) =a-2a-b+2a-4b=a-5b
2(x-3y)-3(4x-2y)=2x-6y-12x+6y=-10x
1-(2a-1)-(3a+3) =1-2a+1-3a-3=-5a-1
2a-3b+[4a-(3a-b)]=2a-3b+4a-3a+b=3a-2b还有一题:3-2(3y+2x)3-2(3y+2x)=3-6y-4x3-2(3y+2x)过程？3-2(3y+2x)=3-(6y+4x)=3-6y-4x