the complete question in the attached figure
Let
A°-----------> the same central angle
For the larger circle
length of larger circle=2*pi*r-------> 2*pi*12-----> 75.36 m
360° (full circle) has a length of------------> 75.36 m
A°-----------------------------------> 16 m
A°=(16)*360/75.36--------> A=76.43°
For the smaller circle
length of smaller circle=2pi*r-------> 2*pi*7.5-----> 47.1 m
360° (full circle) has a length of------------> 47.1 m
76.43°-----------------------------------> X
X=76.43*47.1/360-----> X=10 m ----> length arc of the smaller circle
the answer is
the length arc of the smaller circle is 10 m