1. The problem asks to write the subtraction sentence shown on the number line. 2. The number line shows a point at $\frac{4}{5}$ and a purple arrow moving left labeled $-\frac{4}{10}$ ending at $\frac{2}{5}$. 3. This means we start at $\frac{4}{5}$ and subtract $\frac{4}{10}$ to reach $\frac{2}{5}$. 4. The subtraction sentence is therefore: $$\frac{4}{5} - \frac{4}{10} = \frac{2}{5}$$ 5. The problem states not to reduce the fractions, so we leave them as is. 6. This matches the given equation on the number line. Final answer: $$\frac{4}{5} - \frac{4}{10} = \frac{2}{5}$$