Answer:
The answer is C, 24 units.
Step-by-step explanation:
Let [tex]r_A[/tex] be the radius is circle A and [tex]r_B[/tex] be the radius of circle B.
Radius of circle A is 1/3 of the radius of circle B, or:
[tex]r_A=\frac{1}{3}r_B[/tex]
[tex]3r_A=r_B[/tex]
The sum of their circumferences is [tex]64\pi[/tex]. In other words:
[tex]2\pi r_A +2\pi r_B = 64\pi[/tex]
Substitute [tex]r_B[/tex]:
[tex]2\pi(r_A +r_B)=64\pi[/tex]
[tex]2\pi (r_A +3r_A)=64\pi[/tex]
[tex]4r_A=32, r_A=8[/tex]
[tex]r_B=3r_A, r_B=3(8)=24[/tex]
