IKMC 2027 - Grades 11-12 - Self-study SET 9 - Thematic Batch 3 Question 6

A group has 23 students: 21 speak English, 17 speak Russian, and 13 speak French. What is the greatest possible number who speak all three languages?

Editorial note: The source solution confuses the maximum with the minimum. The printed question and choices are retained; see the correction below.