Because it is assumed that the two arms with unequal arm balance are: x, y,1>; x & gt 1/2 >y； x+y = 1；

The first time is called a, and the second time is called b;

Then: ax = y；; by = x；

a = y/x； b=x/y

a+b = y/x+x/y =(x2+y2)/xy & gt； =2xy/xy=2

a+b & gt； =2 A+B = 2 if and only if a = b =1/2;

If it is simpler, you can give an example.

x = 2/3； y= 1/3

Calculate: a+b=2.5Kg.