Express `-3/5` as a rational number with denominator 30.

Answer

To express \(-\frac{3}{5}\) as a rational number with a denominator of 30, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the current fraction**: We have the fraction \(-\frac{3}{5}\).

2. **Determine the new denominator**: We want to convert this fraction to have a denominator of 30.

3. **Find the multiplication factor**: To find out what we need to multiply the denominator (5) by to get 30, we can perform the following calculation:
\[ \frac{30}{5} = 6 \]
This means we need to multiply both the numerator and the denominator by 6.

4. **Multiply the numerator and denominator**: Now we multiply the numerator and the denominator of \(-\frac{3}{5}\) by 6:
\[ -\frac{3 \times 6}{5 \times 6} = -\frac{18}{30} \]

5. **Final result**: Thus, \(-\frac{3}{5}\) expressed as a rational number with a denominator of 30 is:
\[ -\frac{18}{30} \]

### Summary:
The rational number \(-\frac{3}{5}\) can be expressed as \(-\frac{18}{30}\).