Ответ:

4x+11-8x= -4x+11

-7c+9

b-8

1-7y-20y+3-5= -27y-1

5x-8-4x-4+7x= 8x-12

4b-5b-a-a+6b= 5b-2a

3-15a-24a+36= -39a+39

2a-a+(a-5) = 2a-5

13b-9b+c-2b-7b = -5b+c