Question 1050849
<pre><b>
The centers are in red and green below.

You can tell from the number line below that the centers
are 15-10 = 5 units apart.

{{{drawing(500,500,-15,15,-15,15,
circle(0,0,.3),circle(-5,0,.3),circle(0,0,.4),circle(-5,0,.4),
locate(-15,2.3,number_line( 500, 0, 30,10,15  ) ),
circle(0,0,15), circle(-5,0,10) )}}}

Edwin</pre></b>