753.9822368615503771848 meters
How i did it:
50*2*pi+(70*pi*2)
For one it is just 2*r*pi so 50*2*pi, that is:314.1592653589793238
The SMALLER one has a DIAMETER of 50 meters
circumference = pi x dia
pi x50 =
pi*50 = 157.0796 meters