The sum of two rational numbers is - 4. If one of them is `-3/5` find the other.

Answer

To solve the problem step by step, we need to find the other rational number when the sum of two rational numbers is -4, and one of them is -3/5.

### Step-by-Step Solution:

1. **Understand the Problem**: We know that the sum of two rational numbers is -4. One of the numbers is -3/5. Let's denote the other number as \( x \).

2. **Set Up the Equation**: According to the problem, we can write the equation:
\[ -3/5 + x = -4 \]

3. **Isolate \( x \)**: To find \( x \), we need to isolate it on one side of the equation. We can do this by adding \( 3/5 \) to both sides:
\[ x = -4 + 3/5 \]

4. **Convert -4 to a Fraction**: To add these two numbers, we need to express -4 as a fraction with the same denominator as \( 3/5 \). The denominator of \( 3/5 \) is 5, so we can rewrite -4 as:
\[ -4 = -\frac{20}{5} \]

5. **Perform the Addition**: Now we can add the fractions:
\[ x = -\frac{20}{5} + \frac{3}{5} \]
\[ x = \frac{-20 + 3}{5} \]
\[ x = \frac{-17}{5} \]

6. **Conclusion**: Therefore, the other rational number is:
\[ x = -\frac{17}{5} \]

### Final Answer:
The other rational number is \( -\frac{17}{5} \).