The ratio of length to width of a rectangular sheet of paper is 5:3. If the width of the sheet is 18 cm, find its length.

Answer

To find the length of the rectangular sheet of paper given the ratio of length to width and the width itself, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Ratio**: The ratio of length to width is given as 5:3. This means that for every 5 units of length, there are 3 units of width.

2. **Identify the Given Width**: We are given that the width of the sheet is 18 cm.

3. **Set Up the Ratio Equation**: We can express the length (L) and width (W) in terms of the ratio. According to the ratio, we can write:
\[ \frac{L}{W} = \frac{5}{3} \]

4. **Substitute the Given Width**: We know that the width (W) is 18 cm. We can substitute this value into the equation:
\[ \frac{L}{18} = \frac{5}{3} \]

5. **Cross-Multiply to Solve for Length**: To find the length (L), we can cross-multiply:
\[ L \cdot 3 = 5 \cdot 18 \]
Simplifying the right side:
\[ L \cdot 3 = 90 \]

6. **Isolate L**: Now, divide both sides by 3 to find L:
\[ L = \frac{90}{3} = 30 \text{ cm} \]

7. **Conclusion**: The length of the rectangular sheet of paper is 30 cm.