【x-(y-z)】-【(x-y)-z】
=x-y+z-x+y+z
=2z
(8xy-3x²)-5xy-3(xy-2x²+3)
=8xy-3x²-5xy-3xy+6x²-9
=3x²-9
3(x-y)-2(x+y)-5(x-y)+4(x+y)+3(x-y)
=3x-3y-2x-2y-5x+5y+4x+4y+3x-3y
=3x-y
5(2x-3)+4(3-2x)
=10x-15+12-8x
=2x-3
-4x+3(1/3x-2)
=-4x+x-6
=-6-3x
4a-(a-3b)
=4a-a+3b
=3a-3b
a+(5a-3b)-(a-2b)
=a+5a-3b-a+2b
=5a-b
3(2xy-y)-2xy
=6xy-3y-2xy
=4xy-3y