$\text{Let } a = -2.2$ Compute the following:

$\lfloor -2.2 + 1.8\rfloor =$
$\lfloor a + 0.4\rfloor =$
$-\lfloor a - 1.9\rfloor =$
$\lfloor 1.8 a\rfloor =$
$\lfloor a - 2.8\rfloor -\lfloor 0.2\rfloor =$