a) -[a]-[a+b-c]+{-b+c+b-c-2[3c-5b+4a]}
-a-a-b+c+{-b+c+b-c-6c+10b-8a}
2a-b+c-b+c+b-c-6c+10b-8a
-6a+9b+5c
b) -{-[-a-b]-[a-a+b-c]}+{-[-a-b]}
-{a+b-a+a-b+c}+{a+b}
-a-b+a-a+b-c+a+b
b-c
c)-{3m+[-m-m-4]+[-m-n-2n+3]}
-{3m-m+m-4-m-n-2n+3}
-3m+m-m+4+m+n+2n-3
-2m+3n+1
d)-{x+[-x-y-[-x+y-z+x-y]-y]}
-{x-x-y+x-y+z-x+y-y}
-x+x+y-x+y-z+x-y+y
2y-z
espero que este bien y te sirva ... !!!
besos