1,25: (-0,5) - (1,2 0,9 - 2,15 1,2) =

First we need to simplify the expression inside the parenthesis:

1,2 0,9 = 1,08
2,15 1,2 = 2,58

Therefore:

1,25: (-0,5) - (1,08 - 2,58) =

1,25: (-0,5) - (-1,5) =

1,25 + 1,5 = 2,75

So, 1,25: (-0,5) - (1,2 0,9 - 2,15 1,2) = 2,75