Equation of a Circle
We are given the equation:

The equation of a circle of radius r and center (h,k) is:

To convert the given equation into the standard form, we need to complete squares as follows.
First, rearrange terms:

The term 10x is divided by 2x to find the correct number to complete:
10x/(2x) = 5
Similarly, dividing 12y/(2y) = 6
Now we complete both squares by adding (and subtracting) 25 and 36:

Operating:

Second choice