1971 AHSME Problems/Problem 10
Each of a group of girls is blonde or brunette and is blue eyed of brown eyed. If are blue-eyed blondes, are brunettes, and are brown-eyed, then the number of brown-eyed brunettes is
There are brunettes, so there are blondes. We know there are blue-eyed blondes, so there are brown-eyed blondes.
Next, we know that people are brown-eyed, so there are brown-eyed brunettes.
The answer is
-edited by coolmath34