| I got a good analogy from my student today:
if
those who study only German have right eye only, and
those who study only Italian have left eye only, and
those who study both languages have both eyes,
then this question translates:
the total number of students = 30,
the number of right-eyers is 3 more then the number of left-eyers,
the number of two-eyers is the same as the number of one-eyers,
everybody has at least one eye.
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9 right-eyers, 6 left-eyers, 15 two-eyers, 30 altogether. |