The point (4, -7) is reflected across the y-axis. What are the coordinates of its image?

Erklärung

A reflection across the y-axis carries the point straight across it, so its height is untouched and only the x-coordinate changes sign, turning four units to the right into four units to the left. Changing the y-coordinate instead would lift the point above the x-axis, which no reflection across the y-axis can do.