To solve this problem, we need to reflect point $U$ across the line $y = 3$.

Steps to Reflect Point $U$ Across $y = 3$:

1. Find the vertical distance from point $U$ to the line $y = 3$.
2. Reflect the point by moving it the same distance on the opposite side of the line.

Let's go step by step.

1. Identify the coordinates of point $U$ from the image. Based on the grid, point $U$ appears to be at $U(3, 5)$.
2. The line $y = 3$ is horizontal. To reflect $U(3, 5)$ across this line:
   • Point $U$'s y-coordinate is 5.
   • The distance from $y = 5$ to $y = 3$ is $5 - 3 = 2$.
   • Now reflect $U$ by subtracting the distance from 3: $3 - 2 = 1$.

Therefore, the reflection of point $U(3, 5)$ across $y = 3$ is $U'(3, 1)$.

Final Answer:

The coordinates of $U'$ are $(3, 1)$.

Would you like further details or have any questions?

Here are 5 relative questions to expand:

1. How do you reflect points across a vertical line (like $x = \text{constant}$)?
2. What is the general formula for reflecting points across a horizontal line?
3. How does reflecting across the origin differ from reflecting across a line?
4. How would you describe the transformation properties of reflection in terms of distances and angles?
5. Can reflections change the orientation of a figure?

Tip: When reflecting points across a horizontal or vertical line, only one coordinate (either $x$ or $y$) changes, while the other remains the same.