Triangle xyz is reflected across the line x = 3. what is the reflection image of x?

The image of x is the point (7,5).
Draw the line x= 3 and treat it like a mirror.

When you reflect the points of the triangle just count how many units each point is from the mirror (x=3)
Count the same number of points in the opposite direction (away from the mirror) and you will arrive at the coordinates for the points