-3,8-(-8,1+3,9)

To solve the expression \(-3.8 - (-8.1 + 3.9)\), we will follow the order of operations.

1. First, calculate the expression inside the parentheses: \(-8.1 + 3.9 = -4.2\)

2. Now substitute this result back into the original expression: \(-3.8 - (-4.2)\)

3. When subtracting a negative number, it is the same as adding the positive: \(-3.8 + 4.2\)

4. Now, perform the addition: \(-3.8 + 4.2 = 0.4\)

So, the final result is \(\boxed{0.4}\).