There are 18 tens in 180 because if you divide 180 divided by 10, you get 18. you can also do it in your head!!!
Hope this helps!!!
The equation of a circle is (x - h)² + (y - k)² = radius² where (h, k) is the center.
If the diameter is 16, then the radius is 8.
Your equation is:
(x - 7)² + (y + 5)² = 64