Verified answer

1)    8 (а - 7) - 5а = 8а - 56 - 5а = 3а - 56

2)   -3(4x + 1) + 12x = -12x - 3 + 12x = -3

3)  -(b + 1,2) + 3,1b = -b - 1,2 + 3,1b = 2,1b - 1,2

4) - (- 4,5c - 6) - 4,5c = 4,5c + 6 - 4,5c = 6