f- 1( 1/2)=2

Solution:

Solve the equations x+y=3 and x-y= 1 to get x=2 and y= 1.

So under the mapping F, the original image of (3, 1) is (2, 1).

Let x/(x+2)= 1/2 and get x=2 from the correspondence between the original function and the inverse function, that is, f(2)= 1/2.

You can get f- 1( 1/2)=2.