Question: Find the distance between $-1.3$ and $7.9$.
1. **State the problem:** We need to find the distance between the points $-1.3$ and $7.9$ on a number line.
2. **Formula:** The distance between two points $a$ and $b$ on a number line is given by the absolute value of their difference: $$\text{distance} = |b - a|$$
3. **Apply the formula:** Here, $a = -1.3$ and $b = 7.9$, so
$$\text{distance} = |7.9 - (-1.3)|$$
4. **Simplify inside the absolute value:**
$$7.9 - (-1.3) = 7.9 + 1.3 = 9.2$$
5. **Calculate the absolute value:** Since $9.2$ is positive,
$$|9.2| = 9.2$$
6. **Final answer:** The distance between $-1.3$ and $7.9$ is $$9.2$$.