1. **State the problem:** We have a parallelogram GHIJ with vertices G(1, 5), H(8, 7), I(7, 3), and J(0, 1). We need to find the coordinates of the parallelogram after reflecting it across the y-axis. 2. **Reflection rule:** When reflecting a point $(x, y)$ across the y-axis, the x-coordinate changes sign, while the y-coordinate remains the same. The formula is: $$ (x, y) \to (-x, y) $$ 3. **Apply the reflection to each vertex:** - For $G(1, 5)$, reflection gives $G'(-1, 5)$ - For $H(8, 7)$, reflection gives $H'(-8, 7)$ - For $I(7, 3)$, reflection gives $I'(-7, 3)$ - For $J(0, 1)$, reflection gives $J'(0, 1)$ (since $x=0$ remains the same) 4. **Final answer:** The reflected parallelogram G'H'I'J' has vertices: $$ G'(-1, 5), H'(-8, 7), I'(-7, 3), J'(0, 1) $$