#### Answer

center: $(3, 0)$;
radius = 4 units
Refer to the image below for the graph.

#### Work Step by Step

RECALL:
The circle $(x-h)^2+(y-k)^2=r^2$ has its center at $(h, k)$ and a radius of $r$ units.
The given circle can be written as $(x-3)^2+(y-0)^2=4^2$.
This equation is in the same form as the one in the recall part above so its center is at $(3, 0)$ and its radius is $4$ units.
Plot the center.
Then, points that are:
4 units above the center: $(3, 4)$
4 units below the center: $(3, -4)$
4 units to the left of the center: $(-1, 0)$
4 units to the right of the center: $(7, 0)$
Then, connect the points using a curve to form a circle.
(refer to the attached image in the answer part above)