The ratio of the diameters of two circles is 3: 5. the circumference of the larger circle is approximately 113.1 m. what is the approximate circumference of the smaller circle?
7.5 m
22.6 m
67.9 m
188.5 m

Given:
diameter of two circles  3:5
small circle : 3
large circle : 5

circumference of two circles x : 113.1
small circle : ? 
large circle : 113.1 m

3:5 = x :113.1
3*113.1 = 5*x
339.3 = 5x
339.3 / 5 = x
67.86 = x

The approximate circumference of the smaller circle is 67.9 m.

Basic algebra equation. first set up your equation: divide out 9.and now you are left with 2x + 4 = 8.