how do you add two production possibility curves together for two different regions?

 

Information is as follows:

Region A:

X = L^(0.5)

Y = L^(0.5)

 

Region B:

X = 0.5 x L^(0.5)

Y = 0.5 x L^(0.5)

 

Possibility curves:

Region A:

X^2 + Y^2 = 100

 

Region B:

X^2 + Y^2 = 25

 

there for two different regions, so X = Xa in region A, X = Xb in region B, etc.