1) a-(4a-11)+(9-2a)=20-5a
a-4a+11+9-2a=20-5a
20-5a=20-5a
2) 6(3b-4)-5(3b-11)+2=3b+33
18b-24-15b+55+2=3b+33
3b+33=3b+33
3) 10-9(3c-2/3)+7c-16=-2c
10-9c+6+7c-16=-2c
-2c=-2c
1) a-(4a-11)+(9-2a)=20-5a
a-4a+11+9-2a=20-5a
20-5a=20-5a
2) 6(3b-4)-5(3b-11)+2=3b+33
18b-24-15b+55+2=3b+33
3b+33=3b+33
3) 10-9(3c-2/3)+7c-16=-2c
10-9c+6+7c-16=-2c
-2c=-2c