1. **State the problem:** We are given the midpoint $M$ of segment $CD$ with coordinates $(1.5, -12.5)$ and one endpoint $C$ with coordinates $(5, -18)$. We need to find the coordinates of the other endpoint $D$. 2. **Formula for midpoint:** The midpoint $M$ of a segment with endpoints $C(x_1, y_1)$ and $D(x_2, y_2)$ is given by: $$M = \left( \frac{x_1 + x_2}{2}, \frac{y_1 + y_2}{2} \right)$$ 3. **Apply the formula:** We know $M = (1.5, -12.5)$ and $C = (5, -18)$. Let $D = (x, y)$. From the midpoint formula: $$1.5 = \frac{5 + x}{2}$$ $$-12.5 = \frac{-18 + y}{2}$$ 4. **Solve for $x$:** Multiply both sides by 2: $$2 \times 1.5 = 5 + x$$ $$3 = 5 + x$$ Subtract 5 from both sides: $$3 - 5 = x$$ $$\cancel{3} - \cancel{5} = x$$ $$x = -2$$ 5. **Solve for $y$:** Multiply both sides by 2: $$2 \times (-12.5) = -18 + y$$ $$-25 = -18 + y$$ Add 18 to both sides: $$-25 + 18 = y$$ $$\cancel{-25} + \cancel{18} = y$$ $$y = -7$$ 6. **Final answer:** The coordinates of point $D$ are: $$D = (-2, -7)$$