b) \( \left(\frac{3}{5}-1\right): 0, \hat{2}-0,4 \cdot\left(\frac{3}{4}-1\right)+\frac{1}{5}= \)

To solve the expression \( \left(\frac{3}{5}-1\right): 0, \hat{2}-0,4 \cdot\left(\frac{3}{4}-1\right)+\frac{1}{5} \), we will break it down step by step. 1. **Calculate \( \frac{3}{5} - 1 \)**: \[ \frac{3}{5} - 1 = \frac{3}{5} - \frac{5}{5} = \frac{3 - 5}{5} = \frac{-2}{5} \] 2. **Calculate \( \frac{3}{4} - 1 \)**: \[ \frac{3}{4} - 1 = \frac{3}{4} - \frac{4}{4} = \frac{3 - 4}{4} = \frac{-1}{4} \] 3. **Now substitute these values into the expression**: The expression can be rewritten as: \[ \left(\frac{-2}{5}\right) : 0, \hat{2} - 0.4 \cdot \left(\frac{-1}{4}\right) + \frac{1}{5} \] 4. **Calculate \( 0.4 \cdot \left(\frac{-1}{4}\right) \)**: \[ 0.4 \cdot \left(\frac{-1}{4}\right) = \frac{-0.4}{4} = \frac{-0.4}{4} = -0.1 \] 5. **Now substitute this back into the expression**: \[ \left(\frac{-2}{5}\right) : 0, \hat{2} - (-0.1) + \frac{1}{5} \] 6. **Calculate \( -(-0.1) \)**: \[ -(-0.1) = 0.1 \] 7. **Now we have**: \[ 0.1 + \frac{1}{5} \] 8. **Convert \( \frac{1}{5} \) to decimal**: \[ \frac{1}{5} = 0.2 \] 9. **Now add \( 0.1 + 0.2 \)**: \[ 0.1 + 0.2 = 0.3 \] 10. **Final expression**: The expression simplifies to: \[ \left(\frac{-2}{5}\right) : 0, \hat{2} = 0.3 \] Thus, the final result is: \[ \boxed{0.3} \]