Verified answer

Объяснение:

1)a-(4a-3b)=3(b-a)

a-4a+3b=3b-3a

-3a+3b=3b-3a

3b-3a=3b-3a

2)2c=12c-5(2c+3)+15

2c=12c-10c-15+15

2c=12c-10c+0

2c=2c