5a+(3x-3y-4a)
7a+3(a+3b)
(x-y)2-(x-y)2-[(x-y)2-(x-y)2]
a-(a-3b+4c)+3(-c+2b)
(3x2-2xy+7)-(-4x2+5xy+6)
3m^2n+6mn^2-mn^2-m^2n
-3x^2y+5xy^2-6xy^2+4-7x^2y-9
xy^2+(-3x^2y)+4xy^2+(-5x^2y),
(3x-5y)-(6x+7y)+(9x-2y)
2a-[3b-5a-(3a-5b)]
(6m^2n-5mn^2)-6(m^2n-mn^2)
2(4an+2-an)-3an+(an+1-2an+1)-(8an+2+3an)
10a^2b+23ab^2-ba^-32b^a
（7y-3z)-(8y-5z)
这个里面下载去吧,200太多了
