-0.9 - (-0.4) + 0.7  +(-0.7)

To solve this expression, we need to apply the minus sign to each term inside the parentheses.

-0.9 - (-0.4) + 0.7 + (-0.7)

-0.9 + 0.4 + 0.7 - 0.7

Now, we can combine the like terms:

(-0.9 + 0.4) + (0.7 - 0.7)

-0.5 + 0

The final result is -0.5.