Your method is right so u already know how to do it
Keep adding by the same value everytime so start with 10,000 then add 20,000 etc
It is not a circle but you can find the equation of the ellipse.
To do this we need to work out the major and minor radii and the centre
The centre is at (9, 7)
The major (y) radius is 1 and the minor (x) radius is 5
Therefore the equation is (x-9)/5 + (y-7)/1 = 1