5 2 _ : _ 4 15

The ratio provided is \( \frac{5}{4} : \frac{2}{15} \).

To simplify this ratio, we can multiply both sides by the denominators to eliminate the fractions:

1. Start with the original ratio: \[ \frac{5}{4} : \frac{2}{15} \]

2. Convert it into a single ratio by cross-multiplying: \[ 5 \cdot 15 : 2 \cdot 4 \]

3. Calculate each product: \[ 75 : 8 \]

Thus, the simplified form of the ratio \( \frac{5}{4} : \frac{2}{15} \) is \( 75 : 8 \).