What should be subtracted from `- 9/20` to get `-1/5` ?

Answer

To solve the problem of what should be subtracted from \(-\frac{9}{20}\) to get \(-\frac{1}{5}\), we can follow these steps:

### Step-by-Step Solution

1. **Set up the equation**:
We want to find a number \(x\) such that:
\[ -\frac{9}{20} - x = -\frac{1}{5} \]

2. **Rearrange the equation**:
To isolate \(x\), we can add \(x\) to both sides and add \(-\frac{1}{5}\) to both sides:
\[ -\frac{9}{20} + \frac{1}{5} = x \]

3. **Convert \(-\frac{1}{5}\) to a fraction with a denominator of 20**:
We know that:
\[ -\frac{1}{5} = -\frac{4}{20} \quad (\text{because } 1 \times 4 = 4 \text{ and } 5 \times 4 = 20) \]

4. **Substitute the converted fraction back into the equation**:
Now we substitute:
\[ x = -\frac{9}{20} + \left(-\frac{4}{20}\right) \]

5. **Combine the fractions**:
Since both fractions have the same denominator, we can combine them:
\[ x = \frac{-9 - 4}{20} = \frac{-13}{20} \]

6. **Final answer**:
Therefore, the value of \(x\) is:
\[ x = -\frac{13}{20} \]

### Conclusion
So, \(-\frac{13}{20}\) should be subtracted from \(-\frac{9}{20}\) to get \(-\frac{1}{5}\).