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. Let's verify the subtraction: convert fractions to have a common denominator. 5. $\frac{4}{5} = \frac{8}{10}$ and $\frac{2}{5} = \frac{4}{10}$. 6. Subtracting $\frac{4}{10}$ from $\frac{8}{10}$ gives $\frac{8}{10} - \frac{4}{10} = \frac{4}{10}$. 7. This matches the endpoint $\frac{2}{5} = \frac{4}{10}$. 8. Therefore, the subtraction sentence is: $$\frac{4}{5} - \frac{4}{10} = \frac{2}{5}$$ Final answer: $$\frac{4}{5} - \frac{4}{10} = \frac{2}{5}$$