To solve this expression:

(3.9 - 5.8) - (-1 - -7) + 11 45 9

Let's simplify each step:

Now substitute those results back into the expression:

-1.9 - 6 + 11 45 9

Now calculate the multiplication:

11 45 = 495
495 9 = 4455

Now substitute back into the expression:

-1.9 - 6 + 4455

Now add and subtract:

-1.9 - 6 + 4455 = 4447.1

So, the final answer is 4447.1