1)
8b+12b-21b+b=0;
-13c+12c+40c-18c=21c;
10a-a-b+7b=9a+6b;
-15c-15a+8a+4c=-11c-7a;
0,3x+1,6y-0,3x-0,4y=1,2y.
2)
3b+(5a-7b)=3b+5a-7b=-4b+5a;
-3x-(8y-3x)=-3x-8y+3x=-8y;
-(11a+b)-(12a-3b)=-11a-b-12a+3b=
-23а+2b;
3(8a-4)+6a=24a-12+6a=30a-12;
7p-2(3p-1)=7p-6p+2=p+2;
-4(3a+2)+8=-12a-8+8=-12a.