-(5x+y)-7(x-y) -2分之1(x+y)+4分之1(x+2y)
= -5x-y-7x+7y-x/2-y/2+x/4+y/2
= -12x-x/4+6y
= 6y-49x/4
4x-2(x-2) -2x-(3x-1)
=4x-2x+4-2x-3x+1
=5-3x
x-(5x-2y)+2(2x-y)
=x-8x+2y+4x-2y
= -3x
-(5x+y)-7(x-y) -2分之1(x+y)+4分之1(x+2y)
= -5x-y-7x+7y-x/2-y/2+x/4+y/2
= -12x-x/4+6y
= 6y-49x/4
4x-2(x-2) -2x-(3x-1)
=4x-2x+4-2x-3x+1
=5-3x
x-(5x-2y)+2(2x-y)
=x-8x+2y+4x-2y
= -3x