1、(5a+4c+7b)+(5c-3b-6a)
=5a-6a+4c+5c+7b-3b
=-a+9c+4b.
2、(8xy-x^2+y^2)-(x^2-y^2+8xy)
=8xy-x^2+y^2-x^2+y^2-8xy
=2(y^2-x^2).
3、(2x^2-0.5+3x)-4(x-x^2+0.5)
=2x^2-0.5+3x-4x+x^2-0.5
=3x^2+3x-1.
4、 3x^2-[7x-(4x-3)-2x^2]
=3x^2-[7x-4x+3-2x^2]
=3x^2-[3x+3-2x^2]
=3x^2-3x-3+2x^2
=5x^2-3x-3.
5、2x-10.3x
=-8.3x.
6、3x-x-5x
=-3x.
7、-b+0.6b-2.6b
=-3b.
8、m-n^2+m-n^2
=-2n^2+2m.