The equation \(-0.4 = \) can be completed in several ways depending on what you want to express. Here are some options:
- As a decimal: \(-0.4 = -\frac{4}{10} = -\frac{2}{5}\)
- As a fraction: \(-0.4 = -\frac{4}{10}\)
- As a percentage: \(-0.4 = -40%\)
If you have a specific context in mind (like solving for a variable), please provide more details!