The equation for the unemployment rate takes into account only those are within the labor force. Out of the given population of 260 million people, only 200 million of these are within the labor force. This already excludes those who are retired and others.
The unemployment rate is therefore calculated as shown below,
UR = (12 million / 200 million) x 100%
Simplifying,
UR = 6%
Thus, the unemployment rate is equal to 6%.