ANSWER
(x - 2)² + (y - 3)² = 9
Step-by-step explanation
The equation of a circle with center (h, k) and radius r is

In this problem, the center of the circle is point (2, 3) and we don't know the radius, but we do know a point where the circle passes (5, 3). The distance between the center and this point is the radius of the circle:
Since the center and the point are at the same y-coordinate, the distance - and therefore the radius - is the difference between the x-coordinates of the two points:

The equation then is:
