1 3/5:3/8

To solve the ratio \(1 \frac{3}{5} : \frac{3}{8}\), we first need to convert \(1 \frac{3}{5}\) into an improper fraction.

1. Convert \(1 \frac{3}{5}\) to an improper fraction: \[ 1 \frac{3}{5} = \frac{5 \cdot 1 + 3}{5} = \frac{5 + 3}{5} = \frac{8}{5} \]

2. Now the ratio is: \[ \frac{8}{5} : \frac{3}{8} \]

3. To divide by a fraction, we multiply by its reciprocal: \[ \frac{8}{5} \div \frac{3}{8} = \frac{8}{5} \times \frac{8}{3} = \frac{8 \cdot 8}{5 \cdot 3} = \frac{64}{15} \]

4. Therefore, the ratio \(\frac{8}{5} : \frac{3}{8}\) simplifies to: \[ 64:15 \]

Thus, \(1 \frac{3}{5} : \frac{3}{8}\) simplifies to \(64:15\).